trouble getting this circuit to work

[John Grafton]

Came across this circuit to be used as a dual coil ignition coil driver
recently and tried building it. However, despite all efforts, I can't get
it to work:

http://www.capturedlightning.org/hot-streamer/temp/Old2001Files/2001-12/QuadracDriver.pdf

If you read the description, you'll see that the included line voltage
doubler is required if the circuit is to be operated from 120 v line.
Therefore, I am using the doubler also.

Here's all I can get from the circuit. I use between a 25 and 60 watt
incandescent in series with the 120 v input to the doubler for protection of
the circuit. When I plug in the circuit, I hear no sparks nor is there any
hum of the included ignition coil. Sometimes the 60 watt bulb will light
brightly as the circuit is plugged in; othertimes the bulb does not light at
all. Adjusting the variable resistor has no effect on the brightness of the
light bulb if it's on and if no light bulb, pot adjustment won't light it
either. I've been told that the top and middle leads of QD1 need switched
(in other words QD1 top goes to ground and QD1 middle goes to R2/diode
junction). Tried that and still no response.

This seems like it should be a simple circuit to troubleshoot, but I am out
of practice for some time and not sure where to start. I've checked L1 out
of circuit and it still has the proper resistance. I've also replaced the
pot since adjusting it was getting me nothing, and still nothing with a new
pot. The output from the doubler is correct at 300+ volts. Tried switching
ignition primary wires, but still no effect. Instinct tells me that QD1
might be bad. Is there any way I can measure it out of circuit to be sure?
What would resistances be between terminals?

Any suggestions would be greatly appreciated.

Thanks,
John

 

[William Sommerwerck]

Assuming this is a "legitimate" circuit that /should/ work, all I can offer
is the obvious...

Check that all the parts are "good".

Have someone else go over your wiring. It's so easy to make a mistake, even
in such a simple circuit.

 

[Jamie]

Came across this circuit to be used as a dual coil ignition coil driver
recently and tried building it. However, despite all efforts, I can't get
it to work:

http://www.capturedlightning.org/hot-streamer/temp/Old2001Files/2001-12/QuadracDriver.pdf

If you read the description, you'll see that the included line voltage
doubler is required if the circuit is to be operated from 120 v line.
Therefore, I am using the doubler also.

Here's all I can get from the circuit. I use between a 25 and 60 watt
incandescent in series with the 120 v input to the doubler for protection of
the circuit. When I plug in the circuit, I hear no sparks nor is there any
hum of the included ignition coil. Sometimes the 60 watt bulb will light
brightly as the circuit is plugged in; othertimes the bulb does not light at
all. Adjusting the variable resistor has no effect on the brightness of the
light bulb if it's on and if no light bulb, pot adjustment won't light it
either. I've been told that the top and middle leads of QD1 need switched
(in other words QD1 top goes to ground and QD1 middle goes to R2/diode
junction). Tried that and still no response.

This seems like it should be a simple circuit to troubleshoot, but I am out
of practice for some time and not sure where to start. I've checked L1 out
of circuit and it still has the proper resistance. I've also replaced the
pot since adjusting it was getting me nothing, and still nothing with a new
pot. The output from the doubler is correct at 300+ volts. Tried switching
ignition primary wires, but still no effect. Instinct tells me that QD1
might be bad. Is there any way I can measure it out of circuit to be sure?
What would resistances be between terminals?

Any suggestions would be greatly appreciated.

Thanks,
John

You do realize, using a voltage doubler like that, the low side must be
floating on the circuit? or at least away from the mains.

In other words, you can not have your (-) of that circuit to the
common of the supply.

Putting that aside..

It's possible your light bulb load is not allowing the cap to
charge long enough before the trigger circuit fires.




http://webpages.charter.net/jamie_5"

 

[Samuel M. Goldwasser]

You do realize, using a voltage doubler like that, the low side must be
floating on the circuit? or at least away from the mains.

In other words, you can not have your (-) of that circuit to the
common of the supply.

Putting that aside..

It's possible your light bulb load is not allowing the cap to
charge long enough before the trigger circuit fires.

http://webpages.charter.net/jamie_5"

If he's measuring a constant 300 V on the HV input, then that's not
the problem.

You really need an oscilloscope to see what's happening at the junction
of R1 and C1 - it should be sawtooth as C1 charges and eventually
triggers QD1. You can also AC-couple your DMM if it doesn't already
have a blocking capacitor on the AC range and see if there's any
activity there.

--
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[[email protected]]

Came across this circuit to be used as a dual coil ignition coil driver
recently and tried building it.  However, despite all efforts, I can't get
it to work:

 http://www.capturedlightning.org/hot-streamer/temp/Old2001Files/ 2001-...

If you read the description, you'll see that the included line voltage
doubler is required if the circuit is to be operated from 120 v line.
Therefore, I am using the doubler also.

Here's all I can get from the circuit.  I use between a 25 and 60 watt
incandescent in series with the 120 v input to the doubler for protection of
the circuit.  When I plug in the circuit, I hear no sparks nor is there any
hum of the included ignition coil.  Sometimes the 60 watt bulb will light
brightly as the circuit is plugged in; othertimes the bulb does not light at
all.  Adjusting the variable resistor has no effect on the brightness of the
light bulb if it's on and if no light bulb, pot adjustment won't light it
either.  I've been told that the top and middle leads of QD1 need switched
(in other words QD1 top goes to ground and QD1 middle goes to R2/ diode
junction).  Tried that and still no response.

This seems like it should be a simple circuit to troubleshoot, but I am out
of practice for some time and not sure where to start.  I've checked L1 out
of circuit and it still has the proper resistance.  I've also replaced the
pot since adjusting it was getting me nothing, and still nothing with a new
pot.  The output from the doubler is correct at 300+ volts.  Tried switching
ignition primary wires, but still no effect.  Instinct tells me that QD1
might be bad.  Is there any way I can measure it out of circuit to be sure?
What would resistances be between terminals?

Any suggestions would be greatly appreciated.

Thanks,
John

If you use a 'scope as Sam Goldwasser suggested (excellent advice) GET
AN ISOLATION TRANSFORMER !!!

G²

 

[John Grafton]

I got it to work. Bad quadrac and improper schematic. However, I do have
another question. This circuit is made to be able to run two ignition coils
in parallel for maximum output. I have the two GM HEI coils that it calls
for, but they are slightly different and I am unsure how to parallel the HV
side. Better shown than explained:

http://img212.imageshack.us/img212/4968/heicoil1ip2.jpg

Any thoughts would be appreciated.
Thanks,
John