Board only built on mostly local parts
Posted: Mon Aug 19, 2013 1:21 pm
So, after waiting for the snail mail, hunting exotic components and some interrupter shenanigans, there is finally some light.
It's not the first coil i built, but it's the first that isn't a spark gap one.
I've got the board, the tank capacitor and the current transformer, and have to get the rest locally.
IGBTs are rare - FGA were nonexistant, so i used FGH.
While i was able to find optic fibre, receiver and transmitter, it turned out that the receiver was a total black box - no documentation, not even in Chineese. After some random poking on the pins it apparently died.
The transmitter is just an LED, and i think i'll fit a phototransistor and some glue logic into the receiver to get real control.
But for now the interrupter is replaced by a socket with a attiny85 in it, generating a 10us/990us signal:
The sockets are mostly incompatible - here we have similar parts with dissimilar pinouts.
Power socket fits with bolts at the very edge, the fuse box was of slightly wrong size, DC socket with the right pinout was nonexistant.
The largest capacitors that fit the diametre were only 680uF, i assume that should be enough?
Used a 12cm sphere for the top load - two bowls from Ikea taped together.
Not sure how far out of tune it is - the scope probe in the air and the current transformer output both register something between 250khz and 300khz.
I don't trust the grounding in the sockets here (and extension cords with ground pins are non-existant), so counterpoise ground only.
I've been moving slowly, testing signals, looking for solder problems, etc.
Tried the full voltage without logic on - nothing gone boom.
Tried powering it up to 30V, off a stack of AA batteries, and this gives a 1 cm spark.
I think i've got a GO for mains voltage testing.
So, to sum up the questions before the big test (or boom) tomorrow:
-Am i right to assume that if it produces sparks off the batteries, then the circuitry should be mostly correct, and it won't just blow up?
-Would 680uF power capacitors be enough?
-How far out of tune is too far?
*EDIT: Also, how to get the pictures to scroll?
It's not the first coil i built, but it's the first that isn't a spark gap one.
I've got the board, the tank capacitor and the current transformer, and have to get the rest locally.
IGBTs are rare - FGA were nonexistant, so i used FGH.
While i was able to find optic fibre, receiver and transmitter, it turned out that the receiver was a total black box - no documentation, not even in Chineese. After some random poking on the pins it apparently died.
The transmitter is just an LED, and i think i'll fit a phototransistor and some glue logic into the receiver to get real control.
But for now the interrupter is replaced by a socket with a attiny85 in it, generating a 10us/990us signal:
The sockets are mostly incompatible - here we have similar parts with dissimilar pinouts.
Power socket fits with bolts at the very edge, the fuse box was of slightly wrong size, DC socket with the right pinout was nonexistant.
The largest capacitors that fit the diametre were only 680uF, i assume that should be enough?
Used a 12cm sphere for the top load - two bowls from Ikea taped together.
Not sure how far out of tune it is - the scope probe in the air and the current transformer output both register something between 250khz and 300khz.
I don't trust the grounding in the sockets here (and extension cords with ground pins are non-existant), so counterpoise ground only.
I've been moving slowly, testing signals, looking for solder problems, etc.
Tried the full voltage without logic on - nothing gone boom.
Tried powering it up to 30V, off a stack of AA batteries, and this gives a 1 cm spark.
I think i've got a GO for mains voltage testing.
So, to sum up the questions before the big test (or boom) tomorrow:
-Am i right to assume that if it produces sparks off the batteries, then the circuitry should be mostly correct, and it won't just blow up?
-Would 680uF power capacitors be enough?
-How far out of tune is too far?
*EDIT: Also, how to get the pictures to scroll?