|
Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
|
Thread Tools |
30th Oct 2014, 4:40 pm | #1 |
Heptode
Join Date: Nov 2004
Location: Ripon, N.Yorkshire, UK.
Posts: 782
|
Variable HT regulator circuit.
Can anyone point me in the direction of a simple solid-state VV circuit giving up to 100mA or so for adding to an existing 300V valve power supply?
Many thanks, Jim M0JBJ |
30th Oct 2014, 5:52 pm | #2 |
Guest
Posts: n/a
|
Re: Variable HT regulator circuit.
A simple MOSFET source follower will work well, keep in mind the SOA (safe operating area) of any FETs used, you (will?) need a few in parallel. I designed, and implemented, a constant current source at 450V and 10A maximum and ended up with 48 MOSFETs in parallel. OK they where cheap TO220 devices (50p each), in the end it worked out cheaper than a smaller number of bigger ones.
|
30th Oct 2014, 6:35 pm | #3 |
Octode
Join Date: May 2010
Location: Grantham, Lincolnshire, UK.
Posts: 1,177
|
Re: Variable HT regulator circuit.
A Variac with asuitable isolating transformer feeding a choke filter? Not much current limiting though.
|
30th Oct 2014, 7:16 pm | #4 |
Heptode
Join Date: Nov 2004
Location: Ripon, N.Yorkshire, UK.
Posts: 782
|
Re: Variable HT regulator circuit.
Thanks for those suggestions guys. The last Variac I used almost melted when a careless bystander managed to short it out!
|
30th Oct 2014, 7:38 pm | #5 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
|
Re: Variable HT regulator circuit.
This may be useful. Plenty of MOSFETS to choose from.
http://www.eleccircuit.com/the-varia...supply-0-300v/ |
30th Oct 2014, 8:51 pm | #6 |
Heptode
Join Date: Nov 2004
Location: Ripon, N.Yorkshire, UK.
Posts: 782
|
Re: Variable HT regulator circuit.
Cheers,
I've got all those components! Jim |
31st Oct 2014, 12:23 am | #7 |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
|
Re: Variable HT regulator circuit.
|
31st Oct 2014, 12:31 am | #8 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,536
|
Re: Variable HT regulator circuit.
Variable Voltage?
__________________
....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
31st Oct 2014, 10:48 am | #9 |
Heptode
Join Date: Nov 2004
Location: Ripon, N.Yorkshire, UK.
Posts: 782
|
Re: Variable HT regulator circuit.
Yes, that's right.
|
31st Oct 2014, 11:27 am | #10 |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
|
Re: Variable HT regulator circuit.
Thank you. I suspected as such - wasn't sure. I've never seen that abbreviation for "variable voltage" before.
Al. |
31st Oct 2014, 1:46 pm | #11 |
Guest
Posts: n/a
|
Re: Variable HT regulator circuit.
To make the output smoother decouple the gate to the FET with a resistor from the pot and a capacitor to ground, 100k and 1u would do fine.
|
31st Oct 2014, 3:22 pm | #12 |
Heptode
Join Date: Nov 2004
Location: Ripon, N.Yorkshire, UK.
Posts: 782
|
Re: Variable HT regulator circuit.
Cheers Merlin!
|
31st Oct 2014, 3:46 pm | #13 |
Heptode
Join Date: Nov 2004
Location: Ripon, N.Yorkshire, UK.
Posts: 782
|
Re: Variable HT regulator circuit.
This seems to fit the bill - pity it's not in English though!
http://www.jogis-roehrenbude.de/Roeh...fs_Pruefer.htm |
31st Oct 2014, 4:06 pm | #14 |
Octode
Join Date: Oct 2003
Location: Newbury, Berkshire, UK.
Posts: 1,770
|
Re: Variable HT regulator circuit.
__________________
Chris |
31st Oct 2014, 8:40 pm | #15 |
Heptode
Join Date: Nov 2004
Location: Ripon, N.Yorkshire, UK.
Posts: 782
|
Re: Variable HT regulator circuit.
Cheers, that's very useful!
|
1st Nov 2014, 11:18 am | #16 |
Nonode
Join Date: Jun 2007
Location: Coulsdon, London, UK.
Posts: 2,169
|
Re: Variable HT regulator circuit.
When selecting the potentiometer, make sure it can withstand the voltage and power dissipation of your circuit. Most of the standard metal film resistors are only rated up to 350V.
Mosfets that are made with insulated packages like TO-220F are easier to fit to heatsinks. Keep the wiring to the gate of the Mosfet as short as possible. |
1st Nov 2014, 12:00 pm | #17 |
Heptode
Join Date: Nov 2004
Location: Ripon, N.Yorkshire, UK.
Posts: 782
|
Re: Variable HT regulator circuit.
Thanks Silicon - I was wondering about the VR rating. I think I've some old wire wounds and I'll sort out one of those. Yes, it's a pity about the IRF840 not being insulated as I want to use the case as a heatsink, so it's useful to know about the TO-220Fs.
73 |
1st Nov 2014, 8:33 pm | #18 |
Hexode
Join Date: Apr 2007
Location: W Yorks, UK.
Posts: 407
|
Re: Variable HT regulator circuit.
|
1st Nov 2014, 11:32 pm | #19 |
Heptode
Join Date: Nov 2004
Location: Ripon, N.Yorkshire, UK.
Posts: 782
|
Re: Variable HT regulator circuit.
Thanks David; I have some of those I think.
Jim |
2nd Nov 2014, 10:34 pm | #20 | |
Heptode
Join Date: Apr 2014
Location: Wigton, Cumbria, UK.
Posts: 728
|
Re: Variable HT regulator circuit.
Quote:
Thanks |
|