Marked up drawings huh... LOL...Had only MS Paint that let me draw on an existing picture (png, jpeg,e tc) As far as the conventional flow not electron flow, Welcome to my world where conventional flow rules. I may even wire up a house to be smart but as far as the nuts and bolts (circuits), well.....Looking at your marked up drawings showing current flow. Your arrows show conventional flow, not electron flow.
The left hand drawing seems to be correct. However, the right hand drawing shows the current going to the left through D4. During that half cycle, D4 will be reverse biased so the current will go straight down at the right side of D4 and return to the top of the secondary winding of T1.
while your post was for yesterday at 3:59PM. I did not get your post until this evening. I posted two other drawings (even worse than before, lol). that represents the pos and neg waves. are these right.
Will do that with hast.As for voltage doubling, there are two ways. 1) use the transformer wired as an autoformer. All that means is that a winding is placed in series with the winding to which power is applied and phased in such a way that the voltages add. Many transformers have dual primary windings so they can be used on either 120 or 240 volt circuits. For 120, normally, the primaries are connected in parallel. For 240 volt operation, they connect in series with the center connection insulated. Sort of like putting two penlight batteries in parallel or series. This works for AC.
2)To double the DC voltage use capacitors and rectifiers. The theory is that on one half cycle, all the voltage is used to charge the capacitors through a diode. On the other half cycle, the first diode will be reverse biased and not conduct, BUT a second diode will effectively take the charge on the capacitor and ADD it to the source voltage. There are a couple of different configurations on how this is done, but your circuit is one of them. A Google search of "voltage Doubler" should give more detailed information.
Thanks again
Bladerunner
50 volt cap
- Thread starter bladerunner
- Start date
Hi Bladerunner,
I followed this thread with interest, because I own a fence energizer similar to yours which I designed and built in 2001 and it still works fine! Small differences here and there, but basically the same line of thought with the advantage that I already have a mains supply of 230 V AC (in South Africa). This means that I do not need the boost/Auto transformer stage that you have. After rectification, the peak DC volts is about 325V. This charges the capacitor (C3/C4 in your diagram).
Your first half of your T1 primary connects to 120VAC and is in series with the other half, producing 240V AC. This 240 V AC is effectively in series with your C1 and C2 as well as with R1 and R2 (via either D1, D3 or D4, D2). Components C1, C2, R1, R2 and the low voltage winding of transformer T2 insures a high(ish) impedance to limit the current from the mains every time that the SCR is conducting, otherwise you would have had a short circuit during this time. This method is usually employed in transformerles power supplies and can be followed by a rectifier stage followed by a zener diode in some cases.
T2 provides the required mains isolation and should be a double-insulated type with layer-wound HV side. (This means your primary and secondary coils should NOT be wound on top of each other). Furthermore, this transformer should be HOT-DIPPED in insulating varnish and baked in a furnace.
As far as the direction of current flow is concerned, it is fine to assume conventional flow since all electronic components also assume conventional flow (look at all the arrows in diodes, transistors, SCRs etc).
I followed this thread with interest, because I own a fence energizer similar to yours which I designed and built in 2001 and it still works fine! Small differences here and there, but basically the same line of thought with the advantage that I already have a mains supply of 230 V AC (in South Africa). This means that I do not need the boost/Auto transformer stage that you have. After rectification, the peak DC volts is about 325V. This charges the capacitor (C3/C4 in your diagram).
Your first half of your T1 primary connects to 120VAC and is in series with the other half, producing 240V AC. This 240 V AC is effectively in series with your C1 and C2 as well as with R1 and R2 (via either D1, D3 or D4, D2). Components C1, C2, R1, R2 and the low voltage winding of transformer T2 insures a high(ish) impedance to limit the current from the mains every time that the SCR is conducting, otherwise you would have had a short circuit during this time. This method is usually employed in transformerles power supplies and can be followed by a rectifier stage followed by a zener diode in some cases.
T2 provides the required mains isolation and should be a double-insulated type with layer-wound HV side. (This means your primary and secondary coils should NOT be wound on top of each other). Furthermore, this transformer should be HOT-DIPPED in insulating varnish and baked in a furnace.
As far as the direction of current flow is concerned, it is fine to assume conventional flow since all electronic components also assume conventional flow (look at all the arrows in diodes, transistors, SCRs etc).
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Thank you Johnann: The T2 I use is for a fence charger from F-Shock. Its number is 311-129 SAR and has be providing good service. Do you have any suggestions?
If I may, Does the c1 and c2 have anything to do with the timing (pulses) or is it the Diac. A larger one HT 60 would take longer to trip thus, more time between pulses?
Thanks again.
Have a nice day.
Bladerunner
Hi,
If T2 (311-129 SAR) gives good service, keep on using it.
No, C1 and C2 are only used for current limiting from the raw AC supply and have nothing to do with the timing of the pulses.
C6 (C5?) in conjunction with R3 are your timing components for the pulses. (Larger microfarads and/or higher Megohms will increase the period between pulses and vice verso).
The diac can be virtually any one available, since many of them trigger at around 30V. Once this happens, the charge on C6 (or could it be C5? - Not clear from your diagram) is discharged through the gate/cathode of the SCR and it is therefore unlikely that C6 (C5?) will ever be exposed to higher voltage, hence the voltage rating of 50V in your circuit.
If T2 (311-129 SAR) gives good service, keep on using it.
No, C1 and C2 are only used for current limiting from the raw AC supply and have nothing to do with the timing of the pulses.
C6 (C5?) in conjunction with R3 are your timing components for the pulses. (Larger microfarads and/or higher Megohms will increase the period between pulses and vice verso).
The diac can be virtually any one available, since many of them trigger at around 30V. Once this happens, the charge on C6 (or could it be C5? - Not clear from your diagram) is discharged through the gate/cathode of the SCR and it is therefore unlikely that C6 (C5?) will ever be exposed to higher voltage, hence the voltage rating of 50V in your circuit.
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I get broken fencers that are running fast. Since the resistor checks out, it almost certainly has to be the cap (c6--- missed c5#) Of, course with the faster pulses, the less charge to the fence since it does not give enough time for c3-c4 to charge totally ?
As Bill said in a previous post, the c1,c2 caps together are 2.5uf (series) have to take several cycles to charge c3-c4. It is not a problem as long as the pulses are timed accordingly thus allowing a full charge. Would a larger cap (up to 5uf) in this area help or hinder the charger. (Mainly am asking because of the easy availability of AC 7.5uf caps (where two in series = 3.75uf.))
I read somewhere that diacs have different ranges as to where they break and some of these were over 50V. I may have read it wrong. Have read so much lately I am finding it hard to keep straight at my age. LOL
Thanks again and
Have a nice day :>)
Bladerunner
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Playing catch-up on fencer circuit.
Is indicator light a neon?
Does fencer work without it?
It looks to be the scr trigger. In which case power output would not be affected by timing.
However, fast timing, caused by premature firing, would affect power output.
Most fencers and simple strobe lights are triggered by voltage level across the HV buss caps.
Is indicator light a neon?
Does fencer work without it?
It looks to be the scr trigger. In which case power output would not be affected by timing.
However, fast timing, caused by premature firing, would affect power output.
Most fencers and simple strobe lights are triggered by voltage level across the HV buss caps.
The indicator is a neon lamp and only lights when C3/C4 has/have voltage across it; i.e. during charging cycles and then blinks to zero when the SCR fires.Playing catch-up on fencer circuit.
Is indicator light a neon?
Does fencer work without it?
The fencer will work without it. Only for indication of pulses.
Check out the following: http://www.ascapacitor.com/traditional_film.php
Voltage and type of capacitor will determine what physical size, of course, also the space that you have available. All depends on the application.
Now I know why this fellow used this type of transformer. The cost is about $4.50 per unit for the step-down unit vs. the $10-15 for a 120/240 setup transformer.
This really is a mute question. But should a 120-240 step-up transformer be used in conjunction with a full bridge rectifier, would the volts going into the c3.c4 caps be the same as in this set-up (348 VDC)?
Have a nice day: >)
Bladerunner]
Now I know why this fellow used this type of transformer. The cost is about $4.50 per unit for the step-down unit vs. the $10-15 for a 120/240 setup transformer.
This really is a mute question. But should a 120-240 step-up transformer being used in conjunction with a full bridge rectifier supply the same 348 VDCs going into the c3.c4 caps as this setup does ?
Have a nice day: >)
Bladerunner]
Hi,
Your peak theoretical voltage on the c3/c4 caps will be around 339V if you use a normal 4-diode rectifier bridge on 240VAC, whether it be direct from a 240VAC mains or whether it is derived from a step-up transformer which produces 240VAC. (Diode volt drops in a full-wave bridge rectifier amount up to 1.2V to 1.4V and may be ignored in this application - let's say you end up with 338V peak).
Your peak theoretical voltage on the c3/c4 caps will be around 339V if you use a normal 4-diode rectifier bridge on 240VAC, whether it be direct from a 240VAC mains or whether it is derived from a step-up transformer which produces 240VAC. (Diode volt drops in a full-wave bridge rectifier amount up to 1.2V to 1.4V and may be ignored in this application - let's say you end up with 338V peak).
If the voltage released in c3,c4 are the same as what went into them, then the T2 should have a ratio of about 26:1. Does that sound right?
Have a nice day :>)
Bladerunner
Hi Johann:Theoretically correct, but in practice, the values of voltage will be somewhat lower (but you'll not know the difference when you touch the fence wire!).
It appears the caps and T2 get weak or breakdown over time (1-3 years of constant work). The rectifier diodes, resistors and T1 give little problem. Therefore, I think that it would be better for me and the customer to simply replace all the caps and T2 (if needed) when repairing these boxes for the first time. Do you see any other potential weaknesses I have overlooked?
Have a nice day :>)
Bladerunner
Hi Bladerunner,
Yes, capacitors don't really like to be treated like that, therefore capacitors are specially made for this purpose (to be able to be charged and then virtually short-circuited when it discharges through the low impedance of the LV winding of T2). (Imagine the mechanical forces between the plates of the capacitor the moment it is shorted out: a lot of current in a short time, causing a very strong magnetic field between them trying to push them apart). This happens at say, 1 pulse per second, 24/7 and 365 days etc.! At some stage, something gives and the capacitor fails. (pardon me if I give a practical explanation instead of a mathematical one).
Have a look at : http://www.illinoiscapacitor.com/pdf/Papers/pulse_operation_film_capacitors.pdf
Also : http://www.morganelectroceramics.co...ge-ceramic-capacitors/pulse-power-capacitors/
And here you can see the actual forces in action: http://www.powerlabs.org/capexperiments.htm
Transformer windings do the same when subjected to repeating pulses of current. It starts with mechanical movement of turns, no matter how minute. This creates friction, heat and ultimately breakdown of insulation between turns or layers, helped by the high voltage that will easily cause a flash-over internally and then you have to replace!
As was said before, T2 should be a good quality, resin coated coils type and the LV and the HV windings should be separated (using a coil bobbin with space for each).
Failure is mostly on the components subjected to the high and higher voltage discharge pulses. The remaining components usually lasts very, very long.
Yes, capacitors don't really like to be treated like that, therefore capacitors are specially made for this purpose (to be able to be charged and then virtually short-circuited when it discharges through the low impedance of the LV winding of T2). (Imagine the mechanical forces between the plates of the capacitor the moment it is shorted out: a lot of current in a short time, causing a very strong magnetic field between them trying to push them apart). This happens at say, 1 pulse per second, 24/7 and 365 days etc.! At some stage, something gives and the capacitor fails. (pardon me if I give a practical explanation instead of a mathematical one).
Have a look at : http://www.illinoiscapacitor.com/pdf/Papers/pulse_operation_film_capacitors.pdf
Also : http://www.morganelectroceramics.co...ge-ceramic-capacitors/pulse-power-capacitors/
And here you can see the actual forces in action: http://www.powerlabs.org/capexperiments.htm
Transformer windings do the same when subjected to repeating pulses of current. It starts with mechanical movement of turns, no matter how minute. This creates friction, heat and ultimately breakdown of insulation between turns or layers, helped by the high voltage that will easily cause a flash-over internally and then you have to replace!
As was said before, T2 should be a good quality, resin coated coils type and the LV and the HV windings should be separated (using a coil bobbin with space for each).
Failure is mostly on the components subjected to the high and higher voltage discharge pulses. The remaining components usually lasts very, very long.
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All the new parts made the trans (T2) jump its banks and now only get a low voltage/current ? that has no staying power. By that I mean, usually these fencer are low impedence and increase as the resistance on the fence is applied. No this one, simply acts like the old high impedence fencers (grounding out)/. I guess the the current on the 40uf cap c3,c4 was too much for t2. Either that or something else is wrong. Do you have a recommendation for T2 other than building one yourself.\
Have a nice day :>)
Bladerunner
Which new parts did you fit when your trouble started?
Wherever you source T2 from, make sure that the LV and HV windings are totally separated from each other. Secondly, all windings should be layer-wound with proper insulation between layers. Thirdly, the coil sides are potential break-over points, either between different layers or between a layer and the core material, therefore enough gap should be allowed during the construction of the transformer. Last, but not least, it should be heated in a furnace, then dipped in insulating varnish, removed after impregnation and baked until dry and hard.
The current is not directly responsible for the damage done to T2, but rather the associated high voltage spikes that cause a breakdown in insulation, effectively shorting out HV turns, rendering them useless thereafter. This is why I emphasize the importance of a carefully designed and constructed transformer. (Do-it-yourself if you have the time).
Some fence charger manufacturers sell spares for their products and perhaps you should try to get hold of transformers this way.
Good luck!
Wherever you source T2 from, make sure that the LV and HV windings are totally separated from each other. Secondly, all windings should be layer-wound with proper insulation between layers. Thirdly, the coil sides are potential break-over points, either between different layers or between a layer and the core material, therefore enough gap should be allowed during the construction of the transformer. Last, but not least, it should be heated in a furnace, then dipped in insulating varnish, removed after impregnation and baked until dry and hard.
The current is not directly responsible for the damage done to T2, but rather the associated high voltage spikes that cause a breakdown in insulation, effectively shorting out HV turns, rendering them useless thereafter. This is why I emphasize the importance of a carefully designed and constructed transformer. (Do-it-yourself if you have the time).
Some fence charger manufacturers sell spares for their products and perhaps you should try to get hold of transformers this way.
Good luck!
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