Remember to get video.

Smoke is good. Tires or components (preferably tires)

 

There is no resistor between pin 7 and cap.



Intermittant use may work, you may only need a change of values
of the timing components to solve the problem. You can change these
values and still keep the same timing. A little thought now will
produce a better product.



Yes, it should be. Ceramic caps in that range will probably only
offered "non-polarized".

I'm out till tomorrow.

I'm thinking it out right now- How I can package it smaller, and also go to a less-biased RC circuit.

Right now I have everything laying horizontal. It didn't don on me that I could mount everything vertical. Also, I looked at my G-graphs, and I don't see a need for a down-track circuit, so I'm just going to stick with the 2 launch circuits and the shift circuit (which isn't even a circuit, lol).

I'm thinking:

1x 556 timer: http://www.mouser.com/Search/ProductDetail.aspx?R=TLC556INvirtualkey59500000virtualkey595-TLC556IN (1 x 1.37)
(1 spare)

2x 250 uF cap: http://www.mouser.com/ProductDetail/Nichicon/UHD1H271MPD/?qs=sGAEpiMZZMtZ1n0r9vR22dFdY6vms0RhDxaMe44jjes%3d (2 x 0.81)
(one per channel)

I already have 2 5000 ohm pots

4x 220 ohm resistor: http://www.mouser.com/Search/ProductDetail.aspx?R=294-220-RCvirtualkey21980000virtualkey294-220-RC (4 x 0.18)
(one for channel 1 inline, 1 for each MOSFET, 1 spare)

2x 110 ohm resistor: http://www.mouser.com/ProductDetail...=sGAEpiMZZMu61qfTUdNhG1aMK7XKB77ES2R0xY9PZGo= (2 x 0.18)
(one for channel 2 inline, 1 spare)

4x 10Kohm resistor: http://www.mouser.com/ProductDetail...=sGAEpiMZZMu61qfTUdNhG6xwTrVwTvbztWG8y6CHao4= (4 x 0.18)
(2 for each edge-trigger circuit)

4x 0.047uF ceramic disk capacitor: http://www.mouser.com/ProductDetail...=sGAEpiMZZMt1mVBmZSXTPPQUnq7ol7tGrlOpFXN3hGU= (4 x 0.20)
(one for each pin5, one for each edge-trigger circuit)

10 diodes: http://www.mouser.com/ProductDetail...=sGAEpiMZZMtEwUVCuofpuI3LdHjUmCjoAI2UEn3apPc= (10 x 0.23)
(2 for each relay, 1 for each edge-trigger circuit, 6 spare)

I don't see why I couldn't re-use the MOSFETs I have

1x 14pin socket: http://www.mouser.com/ProductDetail...=sGAEpiMZZMs/Sh/kjph1tvt1/mEPT/XoudDvhlAH3XM= (1 x 0.17)

Did I miss anything? That's a total of $8.06 for 28 components. And i'll use another 7x5x3 hobby box. Hopefully that will be the final version and I can call it good?

 

Near as I can figure, this is what the final version will be?

 

Remember to get video.

Smoke is good. Tires or components (preferably tires)

hit up my youtube channel. lol

 

Hello,

I do not see the resistors from outputs of the 556's to the gates of the mosfets.
Also do I miss the back EMF diodes accross the relays coils.

Bertus

 

Hello,

I do not see the resistors from outputs of the 556's to the gates of the mosfets.
Also do I miss the back EMF diodes accross the relays coils.

Bertus

oops, I put diodes where the resistors should be. The diodes go inline to the relay, and around the relay. Is that all I'm missing?

 

Hello,

I do not see the resistors from outputs of the 556's to the gates of the mosfets.
Also do I miss the back EMF diodes accross the relays coils.

Bertus

Let's try this again...



Relay coils and other inductive loads

Like all ICs, the 555 and 556 must be protected from the brief high voltage 'spike' produced when an inductive load such as a relay coil is switched off. The standard protection diode must be connected 'backwards' across the the relay coil as shown in the diagram.
However, the 555 and 556 require an extra diode connected in series with the coil to ensure that a small 'glitch' cannot be fed back into the IC. Without this extra diode monostable circuits may re-trigger themselves as the coil is switched off! The coil current passes through the extra diode so it must be a 1N4001 or similar rectifier diode capable of passing the current, a signal diode such as a 1N4148 is usually not suitable.

edit: make the 10 diodes these: http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/1N4005/?qs=sGAEpiMZZMtEwUVCuofpuI3LdHjUmCjoAI2UEn3apPc%3d

 

So if I go to 250uF

Midpoint of tuning would be 2.5Kohms (halfway of pot)

0.000250 * (2,500 + 110) = 0.6525 seconds

0.000250 * (2,500 + 1500) = 1.0 seconds

minimum would be

0.000250 * (0 + 110) = 0.02 second

0.000250 * (0 + 1500) = 0.375

maximum would be

0.000250 * (5,000 + 110) = 1.2775
0.000250 * (5,000 + 1500) = 1.625


OK, next thought- Since I have 4 5K pots, if 250uF is still too much, is 6Kohm-20Kohms too much resistance to be reliable, if I use a 75uF cap?

So if I go to 75uF

Midpoint of tuning would be 5Kohms (one pot max, one pot min)

0.000075 * (5,000 + 1600) = 0.5 seconds

0.000075 * (5,000 + 8300) = 1.0 seconds

minimum would be

0.000075 * (0 + 1600) = 0.12 second

0.000075 * (0 + 8300) = 0.6225

maximum would be

0.000075 * (10,000 + 1600) = 0.87

0.000075 * (10,000 + 8300) = 1.37

----------------------------------

Basically, I have 2 options:

Use one 5K pot per channel, with 250uF caps, and 110/220 ohm resistors (range: 0.02 to 1.625 seconds)

Use two 5K pot per channel, with 75uF caps, and 1600/8300 ohm resistors (range: 0.12 to 1.37 seconds)

Which option is better? I'm actually liking the second option, because it has a narrow, yet still usefull band, with 2 adjustments. Basically, each pot is worth 3/8 of a second, whereas on the first option, the entire pot is worth over a full second. We want full power as soon and accurately as possible, so I think the second option is better? But is that too much resistance, to cause internal discharge of the capacitor (which would counteract charging, and make the actual period much longer)?

 

1. You need a .1uF cap for bypassing/decoupling
to ground placed as close to pin 14 (Vcc) as
possible to assure stable operation of the chip.
You will also need another larger (100-470uF)
cap accross the power rails to absorb any large
voltage spikes.
POWER SUPPLY BYPASSING or DECOUPLING GOOGLE it!!!.

2. You can replace all of them .05uF (.047 ordered)
to .1uF and operation will not change. This will
simplify your ordering.

3. I would try R/C combinations as follows:

For 1 sec timer: R=100K (1K-2.2K fixed + 200K pot)
C=10uF

For .5 sec timer R=100K (1K-2.2K fixed + 200K pot)
C=4.7uF

Double check the math before ordering.

4. I see you choice for 556 is a CMOS version (TLC556).
I didn't note the temp rating of your particular choice
but a little checking may get you a chip rated for
"higher operating temps" for literally a few cents more.
In your application the Low power consumption of the
CMOS chip itself is not necessary, A "standard" version
such as "LM556" or "NE556" will work just fine. SEEK OUT
DATASHEETS READ THEM. Compare and learn. The datasheet
for particular chip is attached. These datasheets are linked
right on the page you order from.

5. Diodes 1N4005 are a bit overkill 1N4001-1N4004 (or even 1N4148)
are acceptable for the protection diodes.

6. When you get this thing together either build a circuit to trigger
it from a timer continously (ON.....OFF....ON.....OFF) for a period
of time to see how long it lasts or put it in your everyday vehicle
and trigger it once in a while to see if it holds up in the automotive
enviroment (real live testing in a car).

 

Just saw your post

too much resistance to be reliable,

Electricity is pretty tenacious. It will get through.
Test, test, test.

 

But is that too much resistance, to cause internal discharge of the capacitor (which would counteract charging, and make the actual period much longer)?

Capacitor CHARGES through resistors.
Capacitor DISCHARGES directly through pins 1 and 13 (pin 7 on 555).
there is no resistor between Pin 1 and Capacitor (or Pin 13 and capacitor).

 

Capacitor CHARGES through resistors.
Capacitor DISCHARGES directly through pins 1 and 13 (pin 7 on 555).
there is no resistor between Pin 1 and Capacitor (or Pin 13 and capacitor).

"Beware that electrolytic capacitors leak charge which substantially increases the time period if you are using a high value resistor - use the formula as only a very rough guide! "

is 20Kohms "too high" of a value?

http://www.kpsec.freeuk.com/555timer.htm

 

1. You need a .1uF cap for bypassing/decoupling
to ground placed as close to pin 14 (Vcc) as
possible to assure stable operation of the chip.
You will also need another larger (100-470uF)
cap accross the power rails to absorb any large
voltage spikes.
POWER SUPPLY BYPASSING or DECOUPLING GOOGLE it!!!.

2. You can replace all of them .05uF (.047 ordered)
to .1uF and operation will not change. This will
simplify your ordering.

What exactly is the difference? I agree, ordering a big batch of .1uF ceramic disks would make things a little easier. I read about putting a capacitor in parrallel to the input power to patch spikes, where does the other go?

3. I would try R/C combinations as follows:

For 1 sec timer: R=100K (1K-2.2K fixed + 200K pot)
C=10uF

For .5 sec timer R=100K (1K-2.2K fixed + 200K pot)
C=4.7uF

Double check the math before ordering.

see previous post

4. I see you choice for 556 is a CMOS version (TLC556).
I didn't note the temp rating of your particular choice
but a little checking may get you a chip rated for
"higher operating temps" for literally a few cents more.
In your application the Low power consumption of the
CMOS chip itself is not necessary, A "standard" version
such as "LM556" or "NE556" will work just fine. SEEK OUT
DATASHEETS READ THEM. Compare and learn. The datasheet
for particular chip is attached. These datasheets are linked
right on the page you order from.

I didn't know there was a difference

5. Diodes 1N4005 are a bit overkill 1N4001-1N4004 (or even 1N4148)
are acceptable for the protection diodes.

What about the inline protection diodes? The 4001's were the same price, so i just did a big batch of those instead of having 2 different kinds

6. When you get this thing together either build a circuit to trigger
it from a timer continously (ON.....OFF....ON.....OFF) for a period
of time to see how long it lasts or put it in your everyday vehicle
and trigger it once in a while to see if it holds up in the automotive
enviroment (real live testing in a car).

This one that worked, I probably cycled it 100 times in 10 minutes, before it blew up. And that was with the big caps.

 

I will address all of your questions
to the best of my ability , but it might
be a while. (some time tonight)

This one first:

"Beware that electrolytic capacitors leak charge which substantially increases the time period if you are using a high value resistor - use the formula as only a very rough guide! "

is 20Kohms "too high" of a value?

This is one reason why "plenty of adjustment range" is necessary.
Although it may not be "accurate" it WILL be "consistant" at each setting.
Consistancy + adjustability = Stable, but also, good working range.
(You should understand the value in being consistant as a racer.)

That is 200K not 20K.

I cannot say definitively what will produce the the best result.
This is why testing under different conditions is important.

When a "high value" resistor is mentioned without qualification
it could be 10 Ohm or 10 MegaOhm. Find out what they meant.



As I said I will try to each questions in due time.

 

 

that's fine, take your time (i'm triple tasking- watching NASCAR, preparing a powerpoint for class, and cleaning my room).

I think by what they mean, is that if the charging time is so long (say, minutes -> hours), you have such a high resistance, the capacitor starts discharging internally, which hinders the overall charging process. This could mean it could take a loooooong time for it to finally reach a full charge, if it ever does. Dealing with only one half and one full second, I don't think it actually directly applies to what I'm doing?

I'm still liking my second choice- It doesn't use such a big cap that it fries the chip, and it's not so much resistance that it even has the remote chance to internally discharge.

 

With the 1 Meg Pot. at full resistance you get a 2 second delay before relay one engages and a tad over 4 seconds for the second relay.

At 1 ohm resistance on the Pot, you get .4 secs approx. 1st relay, and .8 secs approx for second relay.

Change caps c5 and c6 to get a different range.

The regulator is a low drop out, 12 volt fixed output, and I would suggest incorporating one for dependable operation of the circuit in the future. Linears' LT1086 is a good choice here.

This circuit can be adapted to a sensor input from an opamp with no problem, so a future automated time adaptive control could be developed.

 

With the 1 Meg Pot. at full resistance you get a 2 second delay before relay one engages and a tad over 4 seconds for the second relay.

At 1 ohm resistance on the Pot, you get .4 secs approx. 1st relay, and .8 secs approx for second relay.

Change caps c5 and c6 to get a different range.

The regulator is a low drop out, 12 volt fixed output, and I would suggest incorporating one for dependable operation of the circuit in the future. Linears' LT1086 is a good choice here.

This circuit can be adapted to a sensor input from an opamp with no problem, so a future automated time adaptive control could be developed.

So the regulator will take the 13.8~14.4 volt input, and reduce it to a constant 12VDC? This interests me, I agree, it helps alot (even with alternator and 2 optima's in parrallel, we're still getting vDrop at full power).

I'm parially understanding the schematic you posted, so the regulator supplies Vcc, the left circuit strictly counts the timing of the RC circuit, and the right circuit strictly switches the transistor?

What's the gain of that over what I have now? I appreciate the help, but i'm curious to the advantages.

 

Mostly that it would be simple and easily made and maintained. using a 556 would make it fit in a matchbox, except for lights and controls.

 

Mostly that it would be simple and easily made and maintained. using a 556 would make it fit in a matchbox, except for lights and controls.

I mean, what you posted takes up more room space-wise, than I have now (at least, once it's condensed). Right now, i'm only using one 556. So what does it gain me to use a second, if only one works?

the relays and pots are what take up the space- I could use a 2x4x6" hobby box, but the relays are 3" tall with connectors. So i'm having to use a 3x5x7 box to fit the relays, and wasting a bunch of space. The potsvare normal sized, 1 inch diameter and half inch tall body. I thought about laying the relays down flat in a 2x4x6 box, but I'm not sure if I would have enough room for the circuitry if I did that.