spritzer Posted August 8, 2014 Report Share Posted August 8, 2014 Looks real to me. Quote Link to comment Share on other sites More sharing options...
s_r Posted August 8, 2014 Report Share Posted August 8, 2014 I think I can call this done. 450V, 10mA output current, uses the old sand, and considerably smaller than my huge HV. 1 Quote Link to comment Share on other sites More sharing options...
eggil Posted August 8, 2014 Report Share Posted August 8, 2014 Congratulations on your build! Quote Link to comment Share on other sites More sharing options...
jose Posted August 8, 2014 Report Share Posted August 8, 2014 Nice, I like this look Quote Link to comment Share on other sites More sharing options...
johnwmclean Posted August 8, 2014 Report Share Posted August 8, 2014 Really nice work s_r Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted August 8, 2014 Author Report Share Posted August 8, 2014 if you are going to buy a bunch of transistors the dy294 from ebay is what you need and cheap Quote Link to comment Share on other sites More sharing options...
mypasswordis Posted August 9, 2014 Report Share Posted August 9, 2014 My dy294 doesn't seem to be able to measure Vbr past ~1398V, which my 2SC4686As seem to exceed since they all read the same value. Quote Link to comment Share on other sites More sharing options...
justin Posted August 9, 2014 Report Share Posted August 9, 2014 throw them out then, can't be too safe Quote Link to comment Share on other sites More sharing options...
mypasswordis Posted August 9, 2014 Report Share Posted August 9, 2014 lol Quote Link to comment Share on other sites More sharing options...
headinclouds Posted August 14, 2014 Report Share Posted August 14, 2014 Very nice s-r, what size knob is that one? I must tell that when I was "testing" my last build. I reached in to move the input cable and my knuckle touched the power transistor at 450v. Well it was quite a jolt and I couldn't help but yell "f****** h***". I was wearing the phones at the time and there was a big noise in them also. There was a smell of vapourised flesh and the attached pic shows a neat crater in my knuckle. I am still alive apparently but I don't intend to try it again. Quote Link to comment Share on other sites More sharing options...
s_r Posted August 14, 2014 Report Share Posted August 14, 2014 Ouch. At least it was "only" a jolt and not something far worse... Anyway, the volume knob on my hv is 48mm in diameter. Quote Link to comment Share on other sites More sharing options...
livewire Posted August 15, 2014 Report Share Posted August 15, 2014 Kewl looking fuckle! Quote Link to comment Share on other sites More sharing options...
eggil Posted August 15, 2014 Report Share Posted August 15, 2014 (edited) Man, I am sure that hurt like the dickens! At least you are still alive! Edited August 15, 2014 by eggil Quote Link to comment Share on other sites More sharing options...
DefQon Posted August 15, 2014 Report Share Posted August 15, 2014 (edited) It's a good thing your other hand was not resting on anything metal or conductive. Heard about a guy who use to repair old tube TV's from my tube supplier/amp builder, bloke had 1 hand on a nearby metal chassis and the other probing lethal voltages till the power arced across his hands and finger tips. He still rocking but the damage was severe enough to have damaged the nerves in his right arm. Lethal voltages beaware. Edited August 15, 2014 by DefQon Quote Link to comment Share on other sites More sharing options...
headinclouds Posted August 15, 2014 Report Share Posted August 15, 2014 Thanks guys, yes rumours of my death are greatly exaggerated. But seriously you're right DefQon. It was careless of me and I got off lightly. Quote Link to comment Share on other sites More sharing options...
kh90123 Posted August 19, 2014 Report Share Posted August 19, 2014 (edited) I need some help. I completed the power board. When connected to the transformer, when I measure the top of the 100uF capacitor to ground (refer the attached image), I see -580V there. What could be wrong? I get about -580V on the negative rail, and +500V on the positive rail. Bias voltage is 560V, instead of 580V. I might need to replace the zener. But first I need to figure out why the cap is showing -580V on top of it... At the same time I also hear weird hissing sound. Sounds like one of the caps might blow or something. Please advice. Edited August 19, 2014 by kh90123 Quote Link to comment Share on other sites More sharing options...
spritzer Posted August 19, 2014 Report Share Posted August 19, 2014 That is the + output side so you shouldn't get - anything there Quote Link to comment Share on other sites More sharing options...
kh90123 Posted August 19, 2014 Report Share Posted August 19, 2014 Hmm never mind I fixed the connection. I wasn't sure if we were supposed to use all the taps that say AC420. Hmm just as I was saying, one of my caps blew. Never knew the stuff inside smells so bad. Quote Link to comment Share on other sites More sharing options...
kh90123 Posted August 19, 2014 Report Share Posted August 19, 2014 Ok just to be sure, the CT has to be grounded right? Quote Link to comment Share on other sites More sharing options...
kh90123 Posted August 19, 2014 Report Share Posted August 19, 2014 (edited) OK it just so happened that I had a bad cap. Should complain to Mouser. The one that blew was the bad cap. Either that, or it was shorting through its metal shield. So I raised all the caps a bit to give it some air gap. Now the +ve rail steadies at +505V, and the -ve rail steadies at -505V. But somehow my Pro bias voltage is at 592V, and rising. Maybe I should replace some of the zeners to get to 580V. It's hitting 600V now!!! Btw, the Hioki DT4282 is one of the best multimeter I have ever used. Dare I say, it's better than the Fluke 87V. Edited August 19, 2014 by kh90123 Quote Link to comment Share on other sites More sharing options...
kh90123 Posted August 19, 2014 Report Share Posted August 19, 2014 (edited) OK after some time I finally figured out why my caps were blowing. The Toroidy transformer that I have, although giving out a good 16V-0-16V, doesn't give me 450V. Instead, the output on the secondaries are 487V, both of them. The 680uF caps that I have are only rated to 450V. I don't recall any capacitors at good price that is good up to 500V or 600V, any suggestion? Can I use capacitor of different values to replace the 680uF caps? Edited August 19, 2014 by kh90123 Quote Link to comment Share on other sites More sharing options...
spritzer Posted August 19, 2014 Report Share Posted August 19, 2014 Do not ground the high voltage CT!!!!!!! That's what you are doing wrong. It's only there for transformers for high voltage windings with CT's where we would use the entire winding for the single supply. Quote Link to comment Share on other sites More sharing options...
UFN Posted August 19, 2014 Report Share Posted August 19, 2014 OK after some time I finally figured out why my caps were blowing. The Toroidy transformer that I have, although giving out a good 16V-0-16V, doesn't give me 450V. Instead, the output on the secondaries are 487V, both of them. That sounds normal if there is no load on the transformer as the voltage for any transformer is specified at full load. At idle, you should expect 5-15% higher voltage (percentage depends on the size and core type of the transformer). //UFN Quote Link to comment Share on other sites More sharing options...
kh90123 Posted August 19, 2014 Report Share Posted August 19, 2014 (edited) I see. Thanks. But still the pro bias voltage is hovering around 598V. Still need to change some of the zeners. When I have time tomorrow I will change one of the 150V zener to 130V. The +ve is at 505V, -ve at -505V, so it looks OK now. No more blowing caps. But to be honest, caps blowing is a sight to see. The smoke erupts from the fractured shell on top of the caps, then soon you will be greeted with putrid pungent smell worse than your own worst fart. Edited August 19, 2014 by kh90123 Quote Link to comment Share on other sites More sharing options...
spritzer Posted August 19, 2014 Report Share Posted August 19, 2014 Zeners are +/-10% at the best of times so 600V isn't too bad. Most of mine are around 570V which is just about perfect. Quote Link to comment Share on other sites More sharing options...
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