Low Threshold MOSFET

Started by rickman in sci.electronics.design5 years ago 34 replies

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...


OT: Computer power supply on its side?

Started by John Doe in sci.electronics.design1 year ago 4 replies

My PSU has an "economy mode" that turns off the fan most of the time the computer is barely being used (you know, like posting to USENET)....

My PSU has an "economy mode" that turns off the fan most of the time the computer is barely being used (you know, like posting to USENET). However, naturally the design assumes it will be right side up. Does having it on its side and allowing the fan to stop present any overheating hazard to components? Of course normally heat rises. I just cleaned it out. You know how dirty stuff get...


The 280 pound capacitor

Started by Cursitor Doom in sci.electronics.design4 years ago 36 replies

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 ...


Pre-war capacitor

Started by Anonymous in sci.electronics.design5 years ago 4 replies

I have an old EHT PSU to repair. There are 2 capacitors, one paper, one plywood! The paper cap, which is uncased, tests as: 420nF 11 ohms ESR, 5%...

I have an old EHT PSU to repair. There are 2 capacitors, one paper, one plywood! The paper cap, which is uncased, tests as: 420nF 11 ohms ESR, 5% loss. I've not yet done a dc leak test, which it needs. What do you think of those figures? IME pre-war paper caps are highly suspect. I'd rather establish what I can before subbing it, as the construction of the whole thing is rather char


Mains power puzzle

Started by Phil Allison in sci.electronics.design2 years ago 118 replies

Hi to all my pals, on the bench I have a US made, bass instrument amplifier (Eden) in near new condition. It uses a 600VA toroidal tranny...

Hi to all my pals, on the bench I have a US made, bass instrument amplifier (Eden) in near new condition. It uses a 600VA toroidal tranny in the PSU. The "T5A" 20mm AC fuse installed was blown and also a similar previous fuse, I'm told. Nothing wrong found with the amp when a new fuse was fitted. However, repeated switch on testing shows max, peak inrush surges over 120 amps, either ...


Low voltage negative resistance oscillator design, lessons learned

Started by bitrex in sci.electronics.design2 years ago 121 replies

Don't bother with discretes if you want a negative resistor when you have low psu headroom, all the discrete negative resistance topologies,...

Don't bother with discretes if you want a negative resistor when you have low psu headroom, all the discrete negative resistance topologies, lambda diodes, foldback limiters, etc. are bad at a couple volts and are seriously fussy with respect to how you load them and have lousy tempcos down there. get an AD8515 for 45 cents and save yourself the trouble


Random crashes

Started by Steve Wilson in sci.electronics.design4 years ago 17 replies
PSU

I experienced random load failures during bootup. Nothing made any sense during troubleshooting. I looked at the AC power connector plugged...

I experienced random load failures during bootup. Nothing made any sense during troubleshooting. I looked at the AC power connector plugged into the power supply. The two AC pins are parallel and symmetrical. If the dimensions are perfect, there may be poor contact. I went to the PSU and twisted the two vertical pins slightly. One pin was twisted CCW, the other CW. I plugged in t...


Recommendation of modest priced lab PSU?

Started by Peter Heitzer in sci.electronics.design5 years ago 3 replies

Hello folks, I am in search of a good but not too expensive lab power supply. The Siglent SPD3303X-E looks rather good. It is not really...

Hello folks, I am in search of a good but not too expensive lab power supply. The Siglent SPD3303X-E looks rather good. It is not really cheap (440 Euros incl. VAT) but has some features I like. It has two outputs that can operate independently or in series for higher voltage or in parallel for higher current. It also shows the power consumption of the load which IMO is a must for non entry ...


Network of MCUs with centralized power supply

Started by pozz in sci.electronics.design6 years ago 18 replies

I'm going to develop a network of 10-30 electronic nodes based on MCU. The distance between them could 100m maximum. There is a single centrale...

I'm going to develop a network of 10-30 electronic nodes based on MCU. The distance between them could 100m maximum. There is a single centrale power supply unit (PSU) that gives power to nodes through a low-voltage 12-18Vdc plus/minus cables. I'm thinking about a two-wires half-duplex RS485. I'll have 4 cables (+/- for power and A/B for signals) and the advantage of differential signal...