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Diabolical Artificer · 23rd Sep 2019, 1:08 pm

I have a good selection of zeners, so possible to elliminate a big string.

I was going to replace the pot as you say with a fixed resistive divider... " I would raise the 3.3Ω to 120Ω so that current limiting occurs at about 5mA). " but if full load current demand is up to 60mA is this not wrong? The original circuit is supposed to have a I of 100ma, I'm missing something here I think. AFAIK Q2 in the circuit of pic is off under normal operation.... Ah, think I've twigged, the 5mA you mention is at the base of Q2, therefore this is "magnified by it's hfe, sorry, transistors aren't my strong point.

I'll have a play and report back. Andy.

Edit, typed before Martins reply... I had a look at that circuit Martin, but dismissed it because of the use of the IXCY10M45S, but I suppose I could use any HV rated mosfet yes?

23rd Sep 2019, 1:08 pm	#6
Diabolical Artificer Dekatron Join Date: Jul 2009 Location: Sleaford, Lincs. UK. Posts: 7,669	Re: HV regulation. I have a good selection of zeners, so possible to elliminate a big string. I was going to replace the pot as you say with a fixed resistive divider... " I would raise the 3.3Ω to 120Ω so that current limiting occurs at about 5mA). " but if full load current demand is up to 60mA is this not wrong? The original circuit is supposed to have a I of 100ma, I'm missing something here I think. AFAIK Q2 in the circuit of pic is off under normal operation.... Ah, think I've twigged, the 5mA you mention is at the base of Q2, therefore this is "magnified by it's hfe, sorry, transistors aren't my strong point. I'll have a play and report back. Andy. Edit, typed before Martins reply... I had a look at that circuit Martin, but dismissed it because of the use of the IXCY10M45S, but I suppose I could use any HV rated mosfet yes? __________________ Curiosity hasn't killed this cat...so far.