Title: A Dual Regulated HV DC Power Supply Post by: KK4YY on May 02, 2019, 08:00:33 PM Needing a dual rail HV regulated power supply, and not wanting to buy p-channel mosfets, I put this together and it worked. As can be seen, there are two identical voltage doublers/filters/regulators connected in series and tapped at their junction for the common leg. A dual secondary transformer is required and I had a Triad N-68X isolation transformer on hand. Wiring it "backwards" did the trick. I was worried that the negative rail might oscillate, but it didn't. Maybe I'm just lucky. Most of the components used were items I had in the junk box so the values shown are not specific to the design. The drawing is "as built". I haven't seen this implementation used anywhere else, so I'm posting it here. Don Title: Re: A Dual Regulated HV DC Power Supply Post by: Opcom on May 02, 2019, 10:43:37 PM Very nice! I'm glad to see worked-out linear type MOSFET regulators of one polarity for these voltages. Some things like this were done with tubes back in the old CRT scope days. I appreciate this for tube op-amps. :)
Title: Re: A Dual Regulated HV DC Power Supply Post by: MikeKE0ZUinkcmo on May 03, 2019, 07:09:36 AM FETS make these types of projects SO easy.
I made a few HV and bias, adjustable, regulated supplies (https://mikeharrison.smugmug.com/PROJECTS/Power-Supply-Project/i-gLS93gs/A) so I could run most any tube rig. Title: Re: A Dual Regulated HV DC Power Supply Post by: KK4YY on May 03, 2019, 08:51:49 AM I built this to power a mosfet audio driver that I've been planning for my DX-100.
I could have taken excising power from the transmitter by bridging the LV power supply, but then I would need a p-channel fet to regulate it because there's no way to work this out with a center-tapped transformer. So, I ventured into the unknown (at least to me) and went with this circuit. My thought was to let this supply run constantly and bias the audio driver fets to cut-off during stand-by. This would remove the load from the supply and prevent audio drive to the tube grids during receive. I haven't yet worked-out the details of how I'm going to do that, but it will be part of the T/R switching one way or the other. Don Title: Re: A Dual Regulated HV DC Power Supply Post by: WBear2GCR on May 03, 2019, 09:25:21 AM Hey Don!!
Maybe you could share the supplier of those "0 ufd/400v caps?? :o 8) ;D Title: Re: A Dual Regulated HV DC Power Supply Post by: WBear2GCR on May 03, 2019, 09:34:37 AM FETS make these types of projects SO easy. I made a few HV and bias, adjustable, regulated supplies (https://mikeharrison.smugmug.com/PROJECTS/Power-Supply-Project/i-gLS93gs/A) so I could run most any tube rig. Mike, very nice job! I got worn out just looking at the work that went into it! :D Had to sit down, rest. Did you use a decal for the meter face, or was the paint to keep from the old meter face from bleeding through? No need to sand it off, just flip it over?? _-_- I had no idea that Daystrom was ever in Newark NJ!! Title: Re: A Dual Regulated HV DC Power Supply Post by: KK4YY on May 03, 2019, 05:41:27 PM Bear,
Thanks for noticing the zero cap — I can see that you're paying attention. It's on the drawing because I intend to use a cap there but, being true to "as built", I zeroed it out for this posting. I can tell that I won't be able to get much past your keen eye. ;) Don Title: Re: A Dual Regulated HV DC Power Supply Post by: KK4YY on May 03, 2019, 06:00:02 PM Admittedly, this design is a work-around for not using a p-channel fet. I wondered if I could find a way of doing it. It looked good on paper, so...
About the only time this circuit may be necessary would be where the desired voltage is high enough that p-channel fets aren't available, perhaps above 600V. Don Title: Re: A Dual Regulated HV DC Power Supply Post by: Opcom on May 03, 2019, 08:47:21 PM The regulation quality and simplicity combination is exceeding good compared to similar-function bipolar or vacuum tube circuits. I tried LTspice on it, very nice performance.
Modulator!! Hmm.. a conventional MOSFET audio amp running on a nice regulated +/- 250V supply could destroy many speakers! haha >3KW into 8 Ohms. Title: Re: A Dual Regulated HV DC Power Supply Post by: MikeKE0ZUinkcmo on May 03, 2019, 11:06:03 PM Quote ...No need to sand it off, just flip it over!!... Randy, I'm not that smart, I had to do it the hard way!! ;)Actually just printed it on regular paper with the Lazer, using TONNE (http://www.tonnesoftware.com/) software. Title: Re: A Dual Regulated HV DC Power Supply Post by: KK4YY on May 04, 2019, 08:10:42 AM Patrick, AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
My measurements show... At turn-on the voltage quickly reaches about 98% of the stable voltage. The last 2% takes a few minutes before settling down (the rails track each other well though). This would cause a very small, proportional change of the modulator grid bias of perhaps 0.2%. I could live with that. Better still, letting the supply run constantly eliminates that warm-up characteristic. When I apply a 10k load (24mA) I get an initial 1% voltage drop that slowly settles to about 2%. Considering that there's no thermal compensation or feedback circuitry, I'm well pleased with the result. It should be more than adequate for my application. Thanks for running the sim. Don |