Scr capacitor circuit will not work. why?

Thread Starter

xpyd3r

Joined Jan 14, 2008
9
Okay, so im using an Scr that has its gate rated at 1 watt power dissipation and 4 amp max current. So, I have a 9 volt battery. The battery is attached to a diode, that drops ~.7 volts so I have 8.3 at a junction. One way has a 10k resistor back to ground. The other is a resistor attached to the gate of the Scr. So from what I figured, .75w ( to keep it lower than 1 watt) = 8.3 x I, so my I = .09 A. Then using that I figure that 8.3 V / .09 A = R and R = 100 ohms. It is not working so I'm stumped what I'm doing wrong. Any ideas? Please and Thanks so much guys. (and gals)
 

Thread Starter

xpyd3r

Joined Jan 14, 2008
9
Okay, sorry it isn't any better, I just drew it up quick with Gimp (don't have anything better to make circuits with yet) And I think the diode is backwards, but I did switch it around both ways to make sure that wasn't the problem. So yea...
 

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S_lannan

Joined Jun 20, 2007
246
what is the actual purpose of this circuit?

are you using the scr to latch

or are you using it to rectify ac and chop the waveform?
 

jpanhalt

Joined Jan 18, 2008
11,087
Do you have a common ground reference with the SCR? Simply touching the output of the circuit you have drawn to the gate of an isolated SCR will not cause it to fire. John
 

jpanhalt

Joined Jan 18, 2008
11,087
This should do it (red connection).

Why the 10K resistor? Also, consider making the SCR on the "low side" of the solenoid. That is, put the solenoid on the positive side leading to the SCR anode.

I am just guessing the flash battery supply is isolated from the secondary.

John
 
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