Never came up with a 3.3 zener so I've had a 10K pot on U1C from the get-go. Doesn't seem to touchy. It's one of those 15 turn PCB mounts.
SP
Briggs Speed Sensor
- Thread starter pntrbl
- Start date
SP
Sarge, on the theory that you should never hide nuthin' from you doctor, lawyer, OR mentor, I need to give you a heads up on some design goals for the alternator. The battery bank this contraption will be maintaining has 24v requirements so I'm looking at a pair of 12's in series. The constant draw of the equipment will probably be less than 2 amps so I'm thinking 2 should suffice, but 4 is a possibilty.
What I was hoping to do, and this may be naive on my part, is to dissect a GM alternator and get right to the slip rings that feed the rotor windings myself. Googling has revealed that alternators are all about making the same voltage regardless of rpm, but that little Briggs is a solid 3600. So I'm hoping to control the current to the rotor and pick the output voltage myself.
What's your opinion on alternator rpm BTW? I've read they're safe to 8000. On the theory of less current needed at higher r's I'm planning 2:1 which will put the alternator just north of 7000. A variable pitch pulley on the Briggs to fine tune the load is also an option.
I briefly considered a direct drive between the Briggs and the alternator but I'm assuming 3600 vs 7200 would double the current requirements to the rotor. Considering me and the Nuclear Mig are completely capable of fabricating a reliably adjustable belt system I decided to go ahead and spin it.
Alternator output wise, since the Briggs is a 5.5HP, and a HP is 745 watts, at say 30v to charge 24v, I'm thinking we can get 10-15 amps out of it before the Briggs gets in trouble. THAT remains to be seen tho!
I hope you're enjoying this design process as much as I am Sarge and now that I'm fully awake I'll be hooking up the other side of that TL082.
SP
What I was hoping to do, and this may be naive on my part, is to dissect a GM alternator and get right to the slip rings that feed the rotor windings myself. Googling has revealed that alternators are all about making the same voltage regardless of rpm, but that little Briggs is a solid 3600. So I'm hoping to control the current to the rotor and pick the output voltage myself.
What's your opinion on alternator rpm BTW? I've read they're safe to 8000. On the theory of less current needed at higher r's I'm planning 2:1 which will put the alternator just north of 7000. A variable pitch pulley on the Briggs to fine tune the load is also an option.
I briefly considered a direct drive between the Briggs and the alternator but I'm assuming 3600 vs 7200 would double the current requirements to the rotor. Considering me and the Nuclear Mig are completely capable of fabricating a reliably adjustable belt system I decided to go ahead and spin it.
Alternator output wise, since the Briggs is a 5.5HP, and a HP is 745 watts, at say 30v to charge 24v, I'm thinking we can get 10-15 amps out of it before the Briggs gets in trouble. THAT remains to be seen tho!
I hope you're enjoying this design process as much as I am Sarge and now that I'm fully awake I'll be hooking up the other side of that TL082.
SP
Well, have you considered using a military surplus alternator? They're already designed to charge 24v systems!
But anyway, let's look at your possible power output:
5.5 HP x 745 Watts = 4097.5 Watts
I = P/E
I = 4097.5/28 volts
I = 146.34 Amperes!
Of course, you're not going to actually get that much due to the power lost in the belt drive and inefficiencies in the alternator itself - but even if you get 60% of that, it's still over 87 Amps @ 28V.
As far as how safe alternators are at speed - you'll note that the alternator pulley is generally much smaller than the crankshaft drive pulley, perhaps a 1:3 ratio for a standard vehicle. High-performance autos use a larger alternator pulley to reduce the drag, but they don't charge as well at idle speeds - but I digress. Anyway, with a 1:3 pulley ratio, and a typical engine having a redline around 5,500 RPM, the alternator at redline would be spun up around 16,500 RPM. Note that I'm simply making a guess at these pulley diameters; you'd have to measure them to get real numbers.
Anyway, the faster you spin the alternator, the less current you'll have to feed the rotor in order to maintain a given output power. OTOH, the faster you spin it, the more mechanical drag you'll have to deal with due to the cooling fan, bearing resistance, and aerodynamic drag on the rotor. Of course, you'll need to spin the thing fast enough to ensure that sufficient airflow is pumped through it to keep heat under control.
So, let's consider what alternator you might use. GM makes a high-output 130A alternator - but that's 130A @ 14V (or thereabouts) which is 14*130 = 1,820 Watts. If you double the voltage output, you'll have to cut the output current by half to 65A, keeping the same power output. Otherwise, you'll have a little melt-down.
The problem with the GM high-output alternator is that it's not very rugged, or tolerant of overloads. Here in FL, I had to replace one of them every couple of summers. The high heat and humidity here means running just about every accessory on a vehicle continuously, which generates a lot of heat in the alternator, causing failures primarily in the rectifier bridge and regulator areas.
But if you started off with a military surplus 28V alternator, you would not likely run into those kinds of problems; as they are (if anything) over-engineered. They put out 60A, which is about what you'd get if you fiddled with a high-output GM unit.
I spotted one in E-bay motors that's a take-off from a Jeep. Guy wants $40 for it, or $1/lb. Shipping is pricey @$41 or so.
http://cgi.ebay.com/ebaymotors/M715...002QQitemZ120261622901QQrdZ1QQsspagenameZWD1V
But anyway, let's look at your possible power output:
5.5 HP x 745 Watts = 4097.5 Watts
I = P/E
I = 4097.5/28 volts
I = 146.34 Amperes!
Of course, you're not going to actually get that much due to the power lost in the belt drive and inefficiencies in the alternator itself - but even if you get 60% of that, it's still over 87 Amps @ 28V.
As far as how safe alternators are at speed - you'll note that the alternator pulley is generally much smaller than the crankshaft drive pulley, perhaps a 1:3 ratio for a standard vehicle. High-performance autos use a larger alternator pulley to reduce the drag, but they don't charge as well at idle speeds - but I digress. Anyway, with a 1:3 pulley ratio, and a typical engine having a redline around 5,500 RPM, the alternator at redline would be spun up around 16,500 RPM. Note that I'm simply making a guess at these pulley diameters; you'd have to measure them to get real numbers.
Anyway, the faster you spin the alternator, the less current you'll have to feed the rotor in order to maintain a given output power. OTOH, the faster you spin it, the more mechanical drag you'll have to deal with due to the cooling fan, bearing resistance, and aerodynamic drag on the rotor. Of course, you'll need to spin the thing fast enough to ensure that sufficient airflow is pumped through it to keep heat under control.
So, let's consider what alternator you might use. GM makes a high-output 130A alternator - but that's 130A @ 14V (or thereabouts) which is 14*130 = 1,820 Watts. If you double the voltage output, you'll have to cut the output current by half to 65A, keeping the same power output. Otherwise, you'll have a little melt-down.
The problem with the GM high-output alternator is that it's not very rugged, or tolerant of overloads. Here in FL, I had to replace one of them every couple of summers. The high heat and humidity here means running just about every accessory on a vehicle continuously, which generates a lot of heat in the alternator, causing failures primarily in the rectifier bridge and regulator areas.
But if you started off with a military surplus 28V alternator, you would not likely run into those kinds of problems; as they are (if anything) over-engineered. They put out 60A, which is about what you'd get if you fiddled with a high-output GM unit.
I spotted one in E-bay motors that's a take-off from a Jeep. Guy wants $40 for it, or $1/lb. Shipping is pricey @$41 or so.
http://cgi.ebay.com/ebaymotors/M715...002QQitemZ120261622901QQrdZ1QQsspagenameZWD1V
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I like military surplus! I'll have to do some poking around here locally ....
What I have on hand tho are standard GM alternators off of my old painter vans. I'll cut the stock bracket up for the adj pulley part and besides that, they're as common as dirt. I could wreck a bunch of them!
And wow! Did I miss on calcing the potential output or what? I realize it was a decimal error now. 30v times 10 amps is only 300 and here I was thinking 3000? Those smiley things should have one labeled dummy just for me.
The TL082 is alive, well, and making 5.73v just like the zener. We have achieved Post #29.
Moving on to U1D I'm thinking about ripping it all out and getting some more breadboard practice. With U1D I need the full zener output on different sides of the 339. I'm afraid it'll get looking like a rats nest again. U1C can be on the other side because I gotta get to a pot 1st anyway. If I place U1A and U1D on the same side of the 339 it'll pin out a lot cleaner and be a lot less confusing. I think. LOL!
Along the lines of freeing up a comparator .....
U1B looks like the candidate. If I reverse the inputs on U1A, and initially I did, it goes up when the battery level drops, but then there's no way I could see to get the hysteresis working. So I used U1B to invert the output of U1A.
But I'm thinking there's some natural hysteresis from the 20A starter motor. Right now I'm operating on a re-chargeable battery pack that will start a car, and that 20A motor is bringing it down a couple of volts. Unless I disconnect or pull the rope on the Briggs the circuit won't shut off. Restoring the depleted battery supply won't do it because it's been hysteresis'd all the way down to 11V by the starter!
My battery pack may need to be charged but unless we're operating from a regulated power supply I'm thinking that motor is gonna affect the supply voltage. Even with a real battery it should be enough to drop the + input at U1A some amount of millivolts all by itself. That's what's happening on a larger scale now.
Whaddaya think?
SP
What I have on hand tho are standard GM alternators off of my old painter vans. I'll cut the stock bracket up for the adj pulley part and besides that, they're as common as dirt. I could wreck a bunch of them!
And wow! Did I miss on calcing the potential output or what? I realize it was a decimal error now. 30v times 10 amps is only 300 and here I was thinking 3000?
Those smiley things should have one labeled dummy just for me.The TL082 is alive, well, and making 5.73v just like the zener.
We have achieved Post #29.Moving on to U1D I'm thinking about ripping it all out and getting some more breadboard practice. With U1D I need the full zener output on different sides of the 339. I'm afraid it'll get looking like a rats nest again. U1C can be on the other side because I gotta get to a pot 1st anyway. If I place U1A and U1D on the same side of the 339 it'll pin out a lot cleaner and be a lot less confusing. I think. LOL!
Along the lines of freeing up a comparator .....
U1B looks like the candidate. If I reverse the inputs on U1A, and initially I did, it goes up when the battery level drops, but then there's no way I could see to get the hysteresis working. So I used U1B to invert the output of U1A.
But I'm thinking there's some natural hysteresis from the 20A starter motor. Right now I'm operating on a re-chargeable battery pack that will start a car, and that 20A motor is bringing it down a couple of volts. Unless I disconnect or pull the rope on the Briggs the circuit won't shut off. Restoring the depleted battery supply won't do it because it's been hysteresis'd all the way down to 11V by the starter!
My battery pack may need to be charged but unless we're operating from a regulated power supply I'm thinking that motor is gonna affect the supply voltage. Even with a real battery it should be enough to drop the + input at U1A some amount of millivolts all by itself. That's what's happening on a larger scale now.
Whaddaya think?
SP
One other nice thing about milsurp alternators is that they're all the same! Doesn't matter if it came off a Jeep, a HMMVEE, a 2&1/2 ton, a 5-ton, 7-ton, they're all the same unit.
I see. Well, "on hand" = "free", which is a hard-to-beat price!
LOL! Well, missed decimal places seem to be a pretty common occurance around here!And wow! Did I miss on calcing the potential output or what? I realize it was a decimal error now. 30v times 10 amps is only 300 and here I was thinking 3000?
Good deal! I'm a bit surprised it's that high, but that's because the resistor is 1.2k instead of 1.1k. That's OK though; we can just compensate with the trimmers.The TL082 is alive, well, and making 5.73v just like the zener.
Yeah, it kind of helps to have related things together. Less chances of shorting things out, too!
There ya go. I was hoping you'd figure that out
You'll be surprised at how many parts go away because of that mod.Yep, it's going to drop the Vcc line by at least a volt, probably more like several. Starters are very heavy current loads. Automotive starters can be several hundred Amperes.
What's the deal with your starter interface for the motor? Do you have a ring-gear flywheel on order? Maybe you could get an auto motor flywheel (ring gear adapter, actually) from a junkyard and a matching starter, then weld up a mounting bracket for it? Getting the ring gear adapter centered on the Briggs flywheel will take some fiddling around, but it's a possible approach.
I don't know.
It took several days just to debit my account. No tracking info. I can write to an e-mail address ......Flywheels aren't commonly worn parts so I suspect the seller had to go to Briggs for it and that may be what's causing the delay. I'm needin' it tho. Firing that Briggs with a simple twist on a pot will be a rewarding step forward.
SP
OK, here's the next installment!
Now, if you've moved around the functions of U1A, U1C or U1D besides how I have 'em, or changed other parts around, let me know, OK? Otherwise, my simulation won't be up-to-date, and it'll make it much harder for me to help you out if you run into trouble.
I added RBA1 - just a small resistor to more or less simulate what you're doing with your rheostat.
Note that U1A has been rewired (inputs flipped, hysteresis resistor removed) U1B is an orphan, it's supporting resistors removed. R6 is now Q2's collector source. Note all the goings-on around U1D!
R5 and R7 form a voltage divider network for the high-side input. R7 stays at 220k Ohms. With R5 at 20k, there is about 0.8v of hysteresis. Increasing R5 to 33k increased the hysteresis to 1.45v - and also increased the threshold level where the field power gets turned on to about 6.36v. That's not a bad thing, because you were getting about 7.7v out of the tachometer portion of the circuit - we still have plenty to play with. If we wanted to, we could even re-wire U2A to be a proper low-pass filter rather than what we have now, but that would mean more trips to Radio Shack to pick up stuff. You must be on a first-name basis with the salespeople there by now.
Getting back to the new mods, R16 supplies (roughly) 10mA to the output of U1D, but also sources current to the bases of Q4 and Q5. These are general purpose PNP and NPN (respectively) transistors that are in a voltage follower arrangement. You don't have to use 2N2222/2N2907; you could use 2N4401/2N4403, or basically any complementary small-signal switching transistors capable of 200mA or so current. Whatever voltage they see on their bases, gets placed on their emitters. The beauty of this arrangement is that all of the current passing through the emitters is used to charge/discharge the gate of the MOSFET. Waste not, want more! (or something like that) R17 limits current through the TO-92 three-legged critters to keep them from getting too toasty.
Anyway, since the gate of the MOSFET needs to be at the same potential as the source to be fully cut off, and the base-emitter junction would cause the gate to be floating about 0.6v below the source, R8 was added to be absolutely certain that the MOSFET would cut completely off - otherwise, you'd have a constant drain through the field. R8 means there will be about 1.45mA current through Q4 the entire time Q3 is turned on, but still it's reasonably efficient.
D4 is still in there to guard against reverse EMF from the field winding. The field is represented by a resistor instead of a coil, just so I didn't have to put both a coil and a resistor in there.
Are we having fun yet?
Now, if you've moved around the functions of U1A, U1C or U1D besides how I have 'em, or changed other parts around, let me know, OK? Otherwise, my simulation won't be up-to-date, and it'll make it much harder for me to help you out if you run into trouble.
I added RBA1 - just a small resistor to more or less simulate what you're doing with your rheostat.
Note that U1A has been rewired (inputs flipped, hysteresis resistor removed) U1B is an orphan, it's supporting resistors removed. R6 is now Q2's collector source. Note all the goings-on around U1D!
R5 and R7 form a voltage divider network for the high-side input. R7 stays at 220k Ohms. With R5 at 20k, there is about 0.8v of hysteresis. Increasing R5 to 33k increased the hysteresis to 1.45v - and also increased the threshold level where the field power gets turned on to about 6.36v. That's not a bad thing, because you were getting about 7.7v out of the tachometer portion of the circuit - we still have plenty to play with. If we wanted to, we could even re-wire U2A to be a proper low-pass filter rather than what we have now, but that would mean more trips to Radio Shack to pick up stuff. You must be on a first-name basis with the salespeople there by now.
Getting back to the new mods, R16 supplies (roughly) 10mA to the output of U1D, but also sources current to the bases of Q4 and Q5. These are general purpose PNP and NPN (respectively) transistors that are in a voltage follower arrangement. You don't have to use 2N2222/2N2907; you could use 2N4401/2N4403, or basically any complementary small-signal switching transistors capable of 200mA or so current. Whatever voltage they see on their bases, gets placed on their emitters. The beauty of this arrangement is that all of the current passing through the emitters is used to charge/discharge the gate of the MOSFET. Waste not, want more!
(or something like that) R17 limits current through the TO-92 three-legged critters to keep them from getting too toasty.Anyway, since the gate of the MOSFET needs to be at the same potential as the source to be fully cut off, and the base-emitter junction would cause the gate to be floating about 0.6v below the source, R8 was added to be absolutely certain that the MOSFET would cut completely off - otherwise, you'd have a constant drain through the field. R8 means there will be about 1.45mA current through Q4 the entire time Q3 is turned on, but still it's reasonably efficient.
D4 is still in there to guard against reverse EMF from the field winding. The field is represented by a resistor instead of a coil, just so I didn't have to put both a coil and a resistor in there.
Are we having fun yet?
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I'm wit' ya Sarge! I've got everything wired in except the new mods and have verified that U1D switches low when I rev the Briggs. I was surprised at that. I thought it would switch high but after double checking the inputs I realize it's supposed to go low. When the tach (V-) passes the zener (V+).
I'll have to get some IRFI9Z34G's from Mouser but they're a whole lot faster than the guy I got the flywheel from. Should be here in a few days.
And now it's off to the Shack for a PNP NPN combo.
SP
I'll have to get some IRFI9Z34G's from Mouser but they're a whole lot faster than the guy I got the flywheel from. Should be here in a few days.
And now it's off to the Shack for a PNP NPN combo.
SP
Some notes and questions Sarge, if you would be so kind.
Found 2N2222's and 2N2907's at Radio Shack so we're sporting those at Q4 and Q5, but I forgot to check my stock and neglected to get a 47 ohm resistor for R17 while I was there. Closed now. So I stuck 100 ohms in at R17 that being the smallest I had on hand and I have NOT powered up ... yet.
Seems like it'd be safe enough tho. Just less current thru Q4 and Q5.
I also stumbled across an IRF510 and for $2 it's mine now! But I just noticed it's an N channel and I believe the IRF9Z's are P channel. I don't know what that means but I'm pretty sure the 510 won't work because of it.
Speaking of which, I'm assuming the gate is equivalent to the base in transistor terms. Source is collector? Drain = emitter?
I'm also wondering about simulating the field with a large wattage resistor. 15 watts?
Thanx again Sarge.
SP
Found 2N2222's and 2N2907's at Radio Shack so we're sporting those at Q4 and Q5, but I forgot to check my stock and neglected to get a 47 ohm resistor for R17 while I was there. Closed now. So I stuck 100 ohms in at R17 that being the smallest I had on hand and I have NOT powered up ... yet.
Seems like it'd be safe enough tho. Just less current thru Q4 and Q5.
I also stumbled across an IRF510 and for $2 it's mine now! But I just noticed it's an N channel and I believe the IRF9Z's are P channel. I don't know what that means but I'm pretty sure the 510 won't work because of it.
Speaking of which, I'm assuming the gate is equivalent to the base in transistor terms. Source is collector? Drain = emitter?
I'm also wondering about simulating the field with a large wattage resistor. 15 watts?
Thanx again Sarge.
SP
OK, good deal.
You could use a couple of 100 Ohm resistors in parallel to get 50 Ohms, which is close enough.Well, the idea is to turn the gate on and off quick, but avoid burning up the transistors. If you switch a MOSFET slowly, it's operating in the linear region (high resistance) and it heats up mighty quickly - and when they're hot, their resistance increases, which makes them even hotter!
So, doubling the turn-on time isn't something that we really want to do.Yep - besides, the IRF510 is mighty low current compared to the IRF9Z34. Check out the spec sheet on it. You can get one from Mouser.com, Alldatasheet.com, and a bunch of other places. View what's printed on the Radio Shack package with a jaundiced eye; they're frequently wrong.
That's vaguely right. But, MOSFETS are a whole 'nother critter than BJT's (transistors). The gate is more like a noose; when it's at 0v relative to the source, the current is choked off. When it's 10v relative to the source (-10v for P-channel), it's wide open, and them electrons just stampede right on through. Where ya get in trouble is when the Vgs is just a few volts; then it's like the I-10 freeway at 4pm.
The gate has capacitance, which has to be charged and discharged. It doesn't really draw any current, unlike a transistor. A transistor has hFE, which is current gain. You put some current in the base, and you control more current at the collector; the base current times the hFE. The tough part is that the hFE changes depending upon how much current is flowing through the collector, and temperature has a BIG effect on hFE as well.Well, that's another thing. You could try it. Quite frankly, I'm not sure how much current it's going to take to power the rotor to get the output charge current you need. I've never bothered to check that. You get to be the guinea pig.
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LOL! I am a pig. At least the wife says so .....You get to be the guinea pig.
I went ahead and powered up. Getting a real clean switch at the emitters on Q4 and 5 when the tach comes up. She's a sweet machine.
I'll beam some IRF9's up from Mouser and while I'm waiting I'll dissect a GM alternator.
SP
Do you know which model alternators you have? Or what was the make/model/year/engine size of the van that it came out of?
What I'm thinking is that we can "fool" the built-in regulator, and tell it that it's outputting 13.8v or so less than it actually is. But I haven't opened up one of the newer alternators. If yours came out of a GMC van, it might be one of the older large-frame type alternators. I think those had a rating around 65 Amps, but I'm sure they had several different models, depending on how many accessories were installed.
It might just be easiest to connect up two alternators. You'd have to completely insulate the frame of the high-side alternator though - and it'll need a separate field supply line. In that case, we might wind up having to replace the IRF9Z34 MOSFET with something else, like perhaps a relay Nahhh! Gotta be a better way to do that. Might could use two of those MOSFETS.
Oh, the alternator has to have a load on it to work properly - at least a large capacitor. Otherwise, it'll go bonkers trying to regulate the output, and will likely burn out the regulator really quickly.
As long as you're taking one apart, might as well check the rectifier bridge over good, and clean any dirt/grease/crud out of there using 91% isopropyl alcohol. Don't get the alcohol in the bearings, you'll wash the grease out. Better to just take the bridge out; it's only held in with a couple of screws anyway.
Here's a nice page for GM alternator rebuilding:
http://www.midwesternmedicalmachine.com/~damonfg/alt_rebuild/index.html
About halfway down the page, he refers to an "exciter diode" - that's a three-legged critter with a long arm on it. I've always called it a "diode trio", because that's what's inside it - three diodes. It supplies the power from the stator windings to the regulator via the long arm. It sits right on top of the full-wave rectifier bridge and the brush holder.
Anyway, have a lookie.
Here's another rebuilding page:
http://www.alternatorparts.com/cs130_sbpage1.htm
for the 130A alternator. It has a field service manual. It appears that these guys are different - they don't have an external field supply! That means as soon as the alternator starts spinning, the regulator will automatically start dumping current into the thing; maybe even sooner.
Here's a YouTube video of a guy rebuilding a CS-144 GM alternator:
http://www.youtube.com/watch?v=LdFA6WF8lVg&feature=related
Part 2:
http://www.youtube.com/watch?v=vKbX7mezuFM&feature=user
These are really helpful videos for that particular model. Note that they have a capacitor on the regulator; that's enough of a load so that it can run without a battery and not get burned up. Note that they're also getting the power for the regulator directly from the rectifier bridge, instead of using the older-style "diode trio".
What I'm thinking is that we can "fool" the built-in regulator, and tell it that it's outputting 13.8v or so less than it actually is. But I haven't opened up one of the newer alternators. If yours came out of a GMC van, it might be one of the older large-frame type alternators. I think those had a rating around 65 Amps, but I'm sure they had several different models, depending on how many accessories were installed.
It might just be easiest to connect up two alternators. You'd have to completely insulate the frame of the high-side alternator though - and it'll need a separate field supply line. In that case, we might wind up having to replace the IRF9Z34 MOSFET with something else, like perhaps a relay
Nahhh! Gotta be a better way to do that. Might could use two of those MOSFETS.Oh, the alternator has to have a load on it to work properly - at least a large capacitor. Otherwise, it'll go bonkers trying to regulate the output, and will likely burn out the regulator really quickly.
As long as you're taking one apart, might as well check the rectifier bridge over good, and clean any dirt/grease/crud out of there using 91% isopropyl alcohol. Don't get the alcohol in the bearings, you'll wash the grease out. Better to just take the bridge out; it's only held in with a couple of screws anyway.
Here's a nice page for GM alternator rebuilding:
http://www.midwesternmedicalmachine.com/~damonfg/alt_rebuild/index.html
About halfway down the page, he refers to an "exciter diode" - that's a three-legged critter with a long arm on it. I've always called it a "diode trio", because that's what's inside it - three diodes. It supplies the power from the stator windings to the regulator via the long arm. It sits right on top of the full-wave rectifier bridge and the brush holder.
Anyway, have a lookie.
Here's another rebuilding page:
http://www.alternatorparts.com/cs130_sbpage1.htm
for the 130A alternator. It has a field service manual. It appears that these guys are different - they don't have an external field supply! That means as soon as the alternator starts spinning, the regulator will automatically start dumping current into the thing; maybe even sooner.
Here's a YouTube video of a guy rebuilding a CS-144 GM alternator:
http://www.youtube.com/watch?v=LdFA6WF8lVg&feature=related
Part 2:
http://www.youtube.com/watch?v=vKbX7mezuFM&feature=user
These are really helpful videos for that particular model. Note that they have a capacitor on the regulator; that's enough of a load so that it can run without a battery and not get burned up. Note that they're also getting the power for the regulator directly from the rectifier bridge, instead of using the older-style "diode trio".
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You are a fountain of useful information Sargeant. I've been dissecting and all I've got are the older wimpy 65amp models. 10si is the Delco designation. The van I'm currently using has a CS130 on it but I can't rob that one!
Something tells me if I put enough batteries on the system that 5 horse Briggs will burn one of those 65 amp models down without even trying.
Military's looking better all the time and I'm looking. Shipping on the E-Bay item out here to the Left Coast is $71.80! I did see the name Leece-Neville on it tho and I've stumbled across that very name during my searching. Time to zero in.
SP
Something tells me if I put enough batteries on the system that 5 horse Briggs will burn one of those 65 amp models down without even trying.
Military's looking better all the time and I'm looking. Shipping on the E-Bay item out here to the Left Coast is $71.80! I did see the name Leece-Neville on it tho and I've stumbled across that very name during my searching. Time to zero in.
SP
OK, maybe time to think about putting a couple of the 65 amp units in series. You could basically keep 'em as-is that way (I think) - but if you're wanting to control the field (rotor) externally, you'll have to pull out the diode trio and regulator, and feed the brushes that way. The two connected together will output 65 Amps apiece, or 130 Amps total, or 27.6v x 65 Amps = 1794 Watts. If we take a wild guess at 60% efficiency, that's 2990 Watts. Since your motor puts out around 4100 Watts (5.5 HP x 745W), you can run it at around 3/4 throttle and keep the alternators going full blast. You might even think about rigging up a governor to keep the engine speed constant while under load.
As I mentioned before, you will have to have the high side (+12 to +24) alternator's frame insulated from the other alternator. This could make it a PITA to build a mount for it. You might have to do something like use motor mounts, as they're rubber insulated.
As I mentioned before, you will have to have the high side (+12 to +24) alternator's frame insulated from the other alternator. This could make it a PITA to build a mount for it. You might have to do something like use motor mounts, as they're rubber insulated.
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I thought about running 2 of the 65's. It'd look like a multi-headed monster! LOL! If I used an "L" configuration only one would have to be adjustable for belt tension ....
The regulator and brush holders are separate pieces BTW. It'd be very easy to put some stand offs where the reg used to be and wire direct thru the brushes to the rotor windings. The rotor winding is 3 ohms so I wouldn't think we'd ever see 4 amps per unit. Still well within the IRF9z's capability.
Some results from digging. 8SC3014U seems to be a military designation for a 24v 100 amp alternator but Leece-Neville calls it a 110-298. Interesting too were the graphs I saw where the amp output leveled off at about 6000 rpm.
We're learnin'.
SP
The regulator and brush holders are separate pieces BTW. It'd be very easy to put some stand offs where the reg used to be and wire direct thru the brushes to the rotor windings. The rotor winding is 3 ohms so I wouldn't think we'd ever see 4 amps per unit. Still well within the IRF9z's capability.
Some results from digging. 8SC3014U seems to be a military designation for a 24v 100 amp alternator but Leece-Neville calls it a 110-298. Interesting too were the graphs I saw where the amp output leveled off at about 6000 rpm.
We're learnin'.
SP
Well, I was thinking more like have an alternator on either side of the Briggs flywheel, with two pulleys on the Briggs. That way you would counterbalance the tension on the Briggs crank bearings, possibly reducing the bearing friction.
IKNOWDAT!
It's just that some have diode trios, and some don't. It appears that those which do have diode trios, do not have the internal capacitors. Having a decent-sized capacitor at the alternator is a good idea; it will cut down on noise. I also think that the newer alternators that have the cap inside them have switching regulators. From what I read on the 130 Amp alternator, it has a 400Hz PWM circuit.Ahh, let's see.
I = E/R
I = 14/3
I = 4.666 Amperes
What 'choo calculatin', Willis?
Hmm, interesting. So, if you ran the Briggs at around 3,000 RPM with a 2:1 pulley ratio, the alternators zingin' & singin' at 6,000 RPM, you'd have plenty of power reserve and the alternators would be getting a good bit of cooling air pumped through 'em.
