When the PC is "switched off" by the button connected to the mobo the PSU goes into a quiescent state, yet must supply voltage to the...

When the PC is "switched off" by the button connected to the mobo the PSU goes into a quiescent state, yet must supply voltage to the mobo. What voltages are active on the PSU, and what only comes up when the mobo powers up? -- Dirk http://www.neopax.com/technomage/ - Magick and Technology

I am using the +12VDC from a PC PSU to switch mains using a relay ie when the PC turns on mains power gets supplied to some amplifiers. Do I...

I am using the +12VDC from a PC PSU to switch mains using a relay ie when the PC turns on mains power gets supplied to some amplifiers. Do I need diode protection across the relay coil for when the PC PSU switches off, or do such PSUs have such protection built in? -- Dirk Full Spectrum Praxis : ZERO STATE : http://zerostate.net

I'm looking for 200-250W ATX Pico-PSU power supply. I see on Chinese sites that they sell such things rated at this wattage for 20-30$, for...

I'm looking for 200-250W ATX Pico-PSU power supply. I see on Chinese sites that they sell such things rated at this wattage for 20-30$, for example: https://www.aliexpress.com/item/DC-12V-250W-Pico-ATX-switch-PSU-24pin-MINI-ITX-ATX-High-Power-Su pply/32629921198.html?spm=a2g0s.8937460.0.0.4eb72e0ev6xyVU My questions is: when looking at the components used, general design etc. -- do you,

Here is my 2W +/-45V PSU http://kvisit.com/S_KuKAw See the MSD7342-224ml for coupled inductor. The IRF9640 is overkill but only SC3...

Here is my 2W +/-45V PSU http://kvisit.com/S_KuKAw See the MSD7342-224ml for coupled inductor. The IRF9640 is overkill but only SC3 model available. The control loop should be pretty straight forward. What is the input voltage range desired? I would copy in that neat net + wiring list that you guys use but do not know how. Just learning LTSPICE. Cheers, Harry

Gentlemen, The link below shows a scope trace of the output of a linear PSU (voltage 4.7VDC) with about 300mV of 100Hz ripple riding on it....

Gentlemen, The link below shows a scope trace of the output of a linear PSU (voltage 4.7VDC) with about 300mV of 100Hz ripple riding on it. This PSU is in- circuit under load from the boards it supplies. Normally I would assume a filter capacitor to be at fault here, but they all check out fine so something else is causing this ripple. Note there is a characteristic 'knee' on the high ...

I started using a Tagan 700BZ PSU in my computer a couple of months ago - my first PSU with active PFC. The UPS is a basic one that has served...

I started using a Tagan 700BZ PSU in my computer a couple of months ago - my first PSU with active PFC. The UPS is a basic one that has served me well for 10 years, and outputs a square wave on battery. While setting up this particular combination, I briefly wondered how the PFC circuit would react to working with non-sinusoidal power but then forgot about it - until it died a couple of ...

http://www.ebay.co.uk/itm/NV-UHL4-Electric-Device-42v-Soviet-Student-of-the-USSR-Vintage-Rare-19 88-Russia/111302224559 What is it? It looks a...

http://www.ebay.co.uk/itm/NV-UHL4-Electric-Device-42v-Soviet-Student-of-the-USSR-Vintage-Rare-19 88-Russia/111302224559 What is it? It looks a little like a wallwart psu. But I'm far from convinced. I vaguely recall 42v being used rather than 220v in some places, but don't remember any details. NT

A bit of a long shot, but does anyone know the polarity of the external 4.3V DC power supply jack for a Canon PowerShot A85 Camera? Canon don't...

A bit of a long shot, but does anyone know the polarity of the external 4.3V DC power supply jack for a Canon PowerShot A85 Camera? Canon don't say. Cheers -- Syd

I want a switch mode PSU which will give me two ~2A outputs at 5V above and below a nominal +50V (say +40V to +60V) DC supply, ie +55V and +45V...

I want a switch mode PSU which will give me two ~2A outputs at 5V above and below a nominal +50V (say +40V to +60V) DC supply, ie +55V and +45V from +50V. I can probably work out some fairly clunky ways of doing this, but it seems possible that there's some topology particularly suited to this type of thing. Any thoughts? Cheers -- Clive

I wonder how many of us have old modems/WiFis/Routers salted away in a dark cupboard waiting for the day when they might be needed again for...

I wonder how many of us have old modems/WiFis/Routers salted away in a dark cupboard waiting for the day when they might be needed again for something? (usually helping a charity with their IT needs) The main annoyance is that the wall warts and even laptop PC supplies of old span a crazy range of random voltages and both polarities. And the PSU often dies or simply gets lost leaving t...

Hi folks. I'm looking to choose a couple of oscillators for 3rd world construction/use, and I'm very rusty on the properties of the numerous...

Hi folks. I'm looking to choose a couple of oscillators for 3rd world construction/use, and I'm very rusty on the properties of the numerous options. What's essential: - reasonably frequency stable with quite widely varying psu voltage, eg 5-9v - discrete parts only, ICs can't be counted on to be available - common parts only, no tapped inductors etc - the minimum of parts is a major choice fa...

Hey y'all big tie and polyester suit fans. There's a lot of vintage surplus S-100 stuff on eBay and elsewhere. What's the bare minimum one...

Hey y'all big tie and polyester suit fans. There's a lot of vintage surplus S-100 stuff on eBay and elsewhere. What's the bare minimum one would need to get an S-100 retro system up and running? Backplane and PSU, processor board, RAM card, some kind of mass-storage controller, terminal interface....?

Gentlemen, What is currently the best choice of filter capacitor for the PSU section of a high-end signal generator the output of which...

Gentlemen, What is currently the best choice of filter capacitor for the PSU section of a high-end signal generator the output of which (obviously) really needs to be as ripple-free as humanly possible? Just in *GENERAL* terms, please guys; don't want to get bogged down in specifics and calculations at this stage, please! tia, cd

Greetings, gentlemen, I'm attaching a scan of the rectifier board from an HP8547A network analyser. I'm just wondering how the designer(s)...

Greetings, gentlemen, I'm attaching a scan of the rectifier board from an HP8547A network analyser. I'm just wondering how the designer(s) arrived at the choice of value for the caps across the incoming supply from the mains transformer secondary windings (the caps immediately before the bridge rectifiers)? In case you can't make it out, the values are 0.047uF, 0.22uF, 0.47uF and 0.04...

Hi, What is the best choice currently for protecting SMPS circuitry in the event of surge at mains switch-on? I'm talking about the PSU...

Hi, What is the best choice currently for protecting SMPS circuitry in the event of surge at mains switch-on? I'm talking about the PSU sections of oscilloscopes, typically, so under normal working conditions less than one Amp drawn at 240V (as it is here in europe). I read somewhere that the front end of an SMPS momentarily looks like close to a short circuit resulting in very large ...

I bought this printer and scanner combo to print circuit board masks, but it doesn't do a very good job. I've acquired an Epson printer that...

I bought this printer and scanner combo to print circuit board masks, but it doesn't do a very good job. I've acquired an Epson printer that works better. Since the Canon printer has has next to no value on the second hand market, and would just be occupying space, I thought I'd pull it apart and see what could be salvaged. I did get a nice 24V 0.65A PSU, which may come in useful one da...

Hi, We are working on a medical product, which will draw about 3 kW from the mains. This is new territory for us, all our previous products...

Hi, We are working on a medical product, which will draw about 3 kW from the mains. This is new territory for us, all our previous products were a few hundred watts max so an off-the-shelf auto-ranging PSU with a suitable IEC lead was OK for any country in the world. 3 kW is OK for a standard outlet in 220V countries, but for North America, Japan etc we are over the limit for a stan...

I have just found this pretty bizarre idea: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.665.5375&rep=rep1&type=pdf It uses a...

I have just found this pretty bizarre idea: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.665.5375&rep=rep1&type=pdf It uses a transformer to limit the voltage swing at the resonant capacitor. Great, but why wouldn't they use a bidirectional TVS for the same purpose? That wouldn't result in a paper, eh, would it? Best regards, Piotr

I was looking to order some low current MOSFETs and realized all the popular items had thresholds of 3 volts and higher. I would like to use...

I was looking to order some low current MOSFETs and realized all the popular items had thresholds of 3 volts and higher. I would like to use something that turns on pretty well at 3 volts so it won't need a 5 volt PSU. Any suggestions? I'm looking for a TO-92 case preferably but surface mount will be ok too. I could have sworn some years ago I tracked down a number of low threshold...

Hi all, I tore down a Marconi signal generator today. It's been awaiting my attention for quite a while. Can't recall the model number off...

Hi all, I tore down a Marconi signal generator today. It's been awaiting my attention for quite a while. Can't recall the model number off hand but it does 10kHz to 5.4Ghz IIRC. I bought it from some chap who told me it had a faulty smoothing cap in the PSU 'cos it was generating signals with ripple on it. He told me he'd been quoted GBP280 ($387 in US dough as of today's date) for a ...