Capacitor question?

[jrz126]

I'm working on building a strobe light, like the one here http://www.aaroncake.net/circuits/strobe2.htm or this one http://www.hut.fi/Misc/Electronics/circuits/strobo_12v.html

Now the circuit in the first link specifies that I use a .47uF mylar capacitor. I have some .56uF 1000Vdc polypropylene film snubber capacitors. Would it be ok to use one of these instead? Also, would the 0.09uF make a significant difference in the output? I dont want to go blowing my $5 flash tubes.

Oh yeah, and is there a difference between a trim-pot and a regular pot?

Thanks.

 

[BF9000]

Capacitor

Using the larger capacitor should not be a problem. It appears that it is used along with the resistor and potentiometer to control the timing of the flash (frequency). When the capacitor is charged to a voltage that is sufficient to ionize the gas in the neon bulb a spark jumps turning on the SCR and allowing the capacitor to dump it's charge accross the trigger coil. The higher capacitance would only lead to a slightly longer charge time for a fixed resistance and slightly slower discharge through the coil. I suppose, in theory, this would mean less output voltage from the coil (not as large dv/dt at the primary). This should be negligible. In short, I do not see a way that the larger capacitor would damage the flash tube.

I'm not 100% sure about the answer for your next question. From my experience, anything labeled as a "trim pot" seems to be slightly more accurate (usually meaning more turns) and is typically adjusted with a tool or screwdriver. "Pot" seems to be a more general term and usually applies to variable resistors with a knob that can be adjusted by hand. This is the only difference as far as know.

 

[Russlk]

I would expect a "regular" pot to have a knob on it and extend thru the front panel while a "trim" pot is adjusted with a screw driver or tool and is usually mounted on the PC board.