its a potential divider, use ohms law
Vheaterbias = (Rbottom * Vin) /(Rtop + Rbottom)
50 to 70v should be fine.
Thank you guys for kind advice, I will follows Salas advice because don't need to modificate the PSU voltage🙂, I take note for future problems about voltage divider thank you Adam🙂
Cheers
Felipe
No problem. Personally i would drop the 15k resistor a bit, 15v maybe marginal so why risk it.
I built up the first version with BC560C and MPSA92 last week and on the bench with dummy load it took a long time to settle. Twenty minutes after power up and setting it was still dropping 0.1VDC every 15 - 20 seconds. Has anybody else seen this? I don't want to put it in circuit until it is stable on the bench. I'm wondering if I need to learn about temperature compensation or some other wonderful new thing.
Thanks
Thanks
The BJT reference one with MPSA92 drifts more due to 3 tempcos and TO-92 error amp heating up. I remember it taking 10-15mins to settle. Up R4 to 4K7 so it runs less mW on MPSA92 for starters. Best for drift would be the later Jfet ref one with TO-126 driver. An easy to get J201 can work fine too if having no K170, with the trimmer half way at 500R for Rs will give you circa 0.35mA under Vbe potential. You can extrapolate the voltage reference resistor at its drain needed for your targeted voltage output.
Soft recovery 600-1000V Peak Inverse Voltage TO-220 high speed. Do your search of what's available easier to you and has a good reputation.
Fine components IMO. I would choose the 1000V PIV one for use in even higher voltage bridges given the opportunity.
SF4007, formerly TFK, now Vishay. Glass, same specs than 1N4007, but fast/soft recovery
How many do you need? 😉
Mouser, I guess, unless you source your components from the little device close to your keybord! 😀
Joking aside, not in stock, minimum order: 17.200 pcs 😱 The price is good however....
Farnell p.n. 1075754
Or Parts Connexion (if they still stock them)
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I don't explain very well, I ordered these:
FFP04H60STU Fairchild Semiconductor Rectifiers
FFP04H60STU Fairchild Semiconductor Rectifiers
Mouser, I guess, unless you source your components from the little device close to your keybord! 😀
Joking aside, not in stock, minimum order: 17.200 pcs 😱 The price is good however....
Farnell p.n. 1075754
Interesting . On first build the reg would take about 15 seconds to start pulling the voltage down. Now with the R4 = 4K7 it seems to be kicking in right away. Still takes a while to settle but the heatsinks are what was in the drawer and are undersized until I buy the right ones for the job. So far they look good and are not oscillating. I'll step up to one of the later circuit versions after I've used these for a bit.
Thanks again!
You can use a fixed resistor substituting the trimmer as a further step to behaving a bit better. What Vout and ICCS, for what application?
I have a line stage on the go running VT-25s at about Vp=265VDC / Ip = 30mA.
Right now ICCS is set at ~ 60mA. Vin is about 300VDC and I'll push for as high a Vout as I can so as not to change the operating point of the 10Y more than I need to. I just want to see what sort of influence the shunt regulator will have on the preamp circuit. If it it looks good then next I'll raise the B+ by about 20VDC or so to get your recommended 50V across the CCS. If still good I'll do a newer version on a nice clean board !
Right now ICCS is set at ~ 60mA. Vin is about 300VDC and I'll push for as high a Vout as I can so as not to change the operating point of the 10Y more than I need to. I just want to see what sort of influence the shunt regulator will have on the preamp circuit. If it it looks good then next I'll raise the B+ by about 20VDC or so to get your recommended 50V across the CCS. If still good I'll do a newer version on a nice clean board !
