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 assembling a 680v psu delivering upto 85 microamps max. This current is limited on both poles by a string of resistors rated to 1kV. Given...

I'm assembling a 680v psu delivering upto 85 microamps max. This current is limited on both poles by a string of resistors rated to 1kV. Given all this I dont see any reason to use an isolating transformer, is that fair enough? Its for lab use, not public sale. NT

I need +/- 12V from a 5V or 12V supply (PC PSU) to drive precision audio stuff (LM4562). Thinking of using a DC-DC converter eg XP Power or...

I need +/- 12V from a 5V or 12V supply (PC PSU) to drive precision audio stuff (LM4562). Thinking of using a DC-DC converter eg XP Power or C&D. The regulation on these isn't brillant at around 10%, but that shouldn't be a problem. Ripple is typically 0.5% Any advice? Dirk

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 ...

Hi I got a Tek P5205 HV differential probe, but sadly no longer a scope that can interface to the active probe. So, the specification for...

Hi I got a Tek P5205 HV differential probe, but sadly no longer a scope that can interface to the active probe. So, the specification for the Tektronix TekProbe interface defines the need for +5V, +15V, -15V and -5V. Well that I can handle without bying an expensive Tek PSU So, the question is, if I supply those voltages will the probe work, with connecting the data and offset signals...

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 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...

For anybody looking for an inexpensive way to check BW and PM of your PSU's I came across a method using just a scope and signal generator. The...

For anybody looking for an inexpensive way to check BW and PM of your PSU's I came across a method using just a scope and signal generator. The test procedure is outlined in the application note below from National. www.national.com/an/AN/AN-1889.pdf I don't understand why FRA's in the Hz to maybe 2MHz range aren't available for a reasonable price. You could buy a nice used truck for wh...

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....?

I need to pick an opamp, perhaps you could recommend something to look at? Essential: - Unity gain stable - Lowest possible voltage...

I need to pick an opamp, perhaps you could recommend something to look at? Essential: - Unity gain stable - Lowest possible voltage offset - Fast Preferable: - The nearer to rail to rail output the better - Lowest psu voltage possible Not too demanding then :) Cheers!

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

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 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...