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Old 3rd November 2010, 10:49 PM   #1241
adamus is offline adamus  United Kingdom
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Quote:
Originally Posted by merlin el mago View Post
You are right, but I have no idea to calculate the right resistor value without change bias for heater supply, how can calculate?
its a potential divider, use ohms law

Vheaterbias = (Rbottom * Vin) /(Rtop + Rbottom)

50 to 70v should be fine.
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Old 3rd November 2010, 10:57 PM   #1242
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Quote:
Originally Posted by Salas View Post
The MJE's resistor is better at 5K6. If having 180V in its enough for having stable 165Vout. Use the reg's trimmer to adjust. The trimmer has its middle pin connected to its lower pin. Rheostat. Measure drop across 15K. Drop/15K=Running current. Adjust value using Ohm's law for whatever you need.
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Edit - double post, see next post

Salas - we are talking about different resistors. Instead of the marginal 180v in, by changing the PS we can get a higher V in (there is a large voltage ddropping R in the PS circuit , the 15k)

Cheers

adam.

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
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Old 3rd November 2010, 11:02 PM   #1243
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Originally Posted by merlin el mago View Post
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.
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Old 3rd November 2010, 11:27 PM   #1244
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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
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Old 3rd November 2010, 11:40 PM   #1245
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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.
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Old 4th November 2010, 12:00 PM   #1246
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Advice best diodes for rectification 1N4007? manufacturer? other diode?
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Old 4th November 2010, 12:25 PM   #1247
Salas is offline Salas  Greece
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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.
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Old 4th November 2010, 12:52 PM   #1248
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What about these

Digi-Key - APT15DQ100KG-ND (Manufacturer - APT15DQ100KG)

http://es.mouser.com/ProductDetail/F...2bSYrMoRNSM%3d

Last edited by merlin el mago; 4th November 2010 at 01:04 PM.
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Old 4th November 2010, 01:16 PM   #1249
Salas is offline Salas  Greece
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Fine components IMO. I would choose the 1000V PIV one for use in even higher voltage bridges given the opportunity.
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Old 4th November 2010, 01:32 PM   #1250
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Yes was also mine first election but I have to place an order to Mouser.
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