Burning is learning
Hi,
Yep that's exactly what I've tried
The meter survived but a fuse, a potentiometer and a 2N3055 burned (F1, R1 and T1 in the first circuit included).
It might sound stupid but I'm learning a lot this way and I've tried not to blow the same component over and over (which is insanity) but a different one each time
Ok seriuously, I've rebuild the thing and re tested both circuit. The first one is behaving as expected, supplying 0-12V and 0-50V (with a running fan cooling heatsinks for B1, T1, IC1 and IC2).
When supplied by the first circuit, the second circuit produce a nice square wave pulse ( in the scope I just bought) when connected to the Emiter of T1 (BU508D), and I'm able to control pulse frequency with R1.
The problem arise when I connect T1 Emiter to Pin 1 of the flyback (DCF 2077A) and Pin 2 to the 53V supply from circuit 1.
With nothing connected between Pin 3 (HV 30KV) and Pin 4 (0V) of the flyback (no meter or anything ) it shorted the circuit ( I've only partially burned R1 of the supply circuit this time)!
I understand that I've put 53V to ground in a sense but isn't it the way to feed the flyback?
Anyone sees a major flaw in the circuits design? If not I'll simply re check everything again to make sure I didn't simply connected something where it doesn't belong!
I might have misidentified the flyback pin so I've included the pin diagram. Pin 1 - 2 are the same in the circuit and the diagram.
Pin 3 is a big rubber plug so it is easy to identified.
Pin 4 in the circuit should be pin 6 on the diagram ???
Thank in advance for any advice!!!
PS I need current to obtain 30KV in the flyback so I dont want to limit it!
Are you saying that you tried to measure current across a voltage source? It's kinda amazing your meter survived.
Anyway, the transistor tried to do the right thing by sacrificing itself to try to protect the fuse. (That's simply an amusing way of saying that semiconductors can die a lot faster than fuses can blow.)
If you want to limit the current then you're going to need something to do that, it won't just happen.
A simple way involves a low value resistor in series with your load that turns on a transistor when the voltage across it hits about 0,6 volts. As the transistor turns on, it shunts current away from the base of the pass transistor leading to a lower voltage output (and thus hopefully a lower current requirement)
When you post the circuit I'll try to show you how to add current limiting to it.
Note that current limiting is no panacea. You may have to cope with the entire power being dissipated in your pass transistor (for a dead short). And that's likely to make it get very hot, very quickly.
Hi,
Yep that's exactly what I've tried
The meter survived but a fuse, a potentiometer and a 2N3055 burned (F1, R1 and T1 in the first circuit included).
It might sound stupid but I'm learning a lot this way and I've tried not to blow the same component over and over (which is insanity) but a different one each time
Ok seriuously, I've rebuild the thing and re tested both circuit. The first one is behaving as expected, supplying 0-12V and 0-50V (with a running fan cooling heatsinks for B1, T1, IC1 and IC2).
When supplied by the first circuit, the second circuit produce a nice square wave pulse ( in the scope I just bought) when connected to the Emiter of T1 (BU508D), and I'm able to control pulse frequency with R1.
The problem arise when I connect T1 Emiter to Pin 1 of the flyback (DCF 2077A) and Pin 2 to the 53V supply from circuit 1.
With nothing connected between Pin 3 (HV 30KV) and Pin 4 (0V) of the flyback (no meter or anything ) it shorted the circuit ( I've only partially burned R1 of the supply circuit this time)!
I understand that I've put 53V to ground in a sense but isn't it the way to feed the flyback?
Anyone sees a major flaw in the circuits design? If not I'll simply re check everything again to make sure I didn't simply connected something where it doesn't belong!
I might have misidentified the flyback pin so I've included the pin diagram. Pin 1 - 2 are the same in the circuit and the diagram.
Pin 3 is a big rubber plug so it is easy to identified.
Pin 4 in the circuit should be pin 6 on the diagram ???
Thank in advance for any advice!!!
PS I need current to obtain 30KV in the flyback so I dont want to limit it!
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