SS SG PCB Layout

[Joster]

Hi All,

Wanted to run a new pcb layout for an ss sg circuit I will be making. I am particularly concerned with the diode output being too close to the ground bus. Any tips would be great.

Thanks!

Joster

[Tom C]

that looks like Ricks old 8 channel board..... I would move the emitter trace over.

Tom C

[Joster]

that looks like Ricks old 8 channel board..... I would move the emitter trace over.

Tom C

excellent point i will make that change thanks Tom C

[Joster]

hows this...

[Joster]

I am also thinking of incorporating some kind of circuit protection. I have a 7 device ss sg that I put alot of work into that is now fried (happened when I was trying to figure out the linear regulator stuff). I am not sure how it fried really...I just saw all the neons glow super bright then they just when out like dominoes. Now when I try to run it nothing happens it just consumes current so im pretty sure all the transistors are done. I suppose I could put a fuse on the trigger bus. I have sourced out ST13009's for this build I wanted mje13009 like I have used before but they are not available from mouser (haven't been for months). They have a max base current of 6 amps but I doubt I would even reach an amp on the trigger bus. Maybe a 2 amp fuse on there and a 2 amp fuse on the top of the power coil? just thinking out loud..any tips would be great...

[Tom C]

that looks better. add a 4.7k ohm resistor in series with the neon that will help a bit. the best protection is hook and unhook protocols... and never work on it when tired or when you have had a few too many
Tom C

[Joster]

yes forsure..I learned my lesson there....no beers and electronics although is seems like a good idea at the time.

i suppose the 4.7 k won't have any negative effect on output....ill add that to the board

I also added dual schottky diodes on each transistor output

So no to the fuses then? I suppose they are not the best for keeping the impedance down anyway.

It will be nice to have good pcb layout made up for anyone interested in etching their own board

[Joster]

ok here is the final added the 4.7k in series with neon and also dual schottky diodes

[Tom C]

that should work. unless you match your schottky you will have one doing more of the work. a single diode is fine.

Tom C

[Tom C]

as far as fuses go.... the circuit makes it hard to actually protect anything. to actually protect the junction you need to prevent the spike from hitting the transistor as soon as the charge battery is disconnected. I don't expect there is a decent way to pass the spike into the junction while at the same time protecting it from over current.

Tom C