Power Supply - Page 1
Forum section: electronics / beginners

author: Ross_mini
author_rank: Unknown
timestamp: October 02, 2016, 06:12:02 pm
content: A have started the LtaoE with my daughter. But I'm looking for a better power supply with current limiting. I have been using a adjustable 'wall wart' 0-12v 400ma for years, but think I should have something more suitable!I've seen this on eBay and after an opinion from you guys.https://www.ebay.co.uk/itm/371600520441I'm a just being a tight arse? Should I be looking at something better? Like the new small rigol one?

author: ataradov
author_rank: Super Contributor
timestamp: October 02, 2016, 06:30:36 pm
content: Those cheap generic power supplies are perfectly fine, especially for hobby use.

author: madires
author_rank: Super Contributor
timestamp: October 02, 2016, 06:47:58 pm
content: Should be fine for a beginner. Seems to be some Mastech clone.

author: retrolefty
author_rank: Super Contributor
timestamp: October 02, 2016, 09:14:57 pm
content: If I was a beginner I might start out with one of these and I would power it with a used laptop power pack.http://www.ebay.com/itm/252531008921?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

author: MosherIV
author_rank: Super Contributor
timestamp: October 03, 2016, 03:45:12 pm
content: A nice bench PSU is definitely worth having.However, at that price, I would suspect that it is a cheap switch mode and not a linear.Siwtchers are OK for digital/Microprocessor work, OK where noise from PSU is not important.Not much good for op-amp or transistor work.

author: setq
author_rank: Frequent Contributor
timestamp: October 03, 2016, 03:55:58 pm
content: Just a heads up if you're doing Learning the Art of Electronics before you buy.You need a dual rail power supply or two independent LINEAR power supplies to complete the text. One has to be variable and supply 0-20v at least. Preferably with a separate 5v supply as well. My favourite power supply (Heathkit IP-2718) does all of this and I think I paid £19 for it off ebay a while ago but you have to camp on it for weeks to find a good deal.Buying two of the supplies you listed would be a good option, only if they are linear, but when you start getting into the £70 territory it's worth looking out for better second hand dual supplies from HP/Thurlby/Weir/Farnell on eBay. Ask on here as well in the wanted section.Some better options if you ask me. Some work may be required but people will help on here and the ROI is higher and they are better supplies for the money:http://www.ebay.co.uk/itm/331986105888(needs recalibration by the sounds)http://www.ebay.co.uk/itm/191985737421(needs a new switch)Or two of these which aren't terrible (I have one):http://www.ebay.co.uk/itm/131634824724

author: Markybhoy
author_rank: Regular Contributor
timestamp: October 03, 2016, 04:17:13 pm
content: If you bought a Heathkit IP-2718 from the states is it just a case of flipping the switch to 240v and changing the plug if you are in the UK?

author: setq
author_rank: Frequent Contributor
timestamp: October 03, 2016, 04:41:37 pm
content: Quote from: Markybhoy on October 03, 2016, 04:17:13 pmYeah definitely. It has a 120/240 switch on the bottom. If it doesn't have an earth wire in the cable I'd replace the mains lead as well. That's a 10 minute job. Just chop the IEC plug of the end of a moulded lead and solder it to the termination points and stick the strain relief back on. It has a tag strip for mains L/N termination 1970s style and a crimp for earth which is commendable.Nice little power supply. Current limit is a hard 500mA per rail and 1.5A on the 5v but that's fine. That's not enough to get you into trouble bar a smoked resistor here and there. Recapping it is less than a tenner. All the parts can be replaced with generic ones. They are three independent supplies so it can deliver up to 45v at 500mA if you stack them.

author: Markybhoy
author_rank: Regular Contributor
timestamp: October 03, 2016, 05:40:06 pm
content: I will be after a power supply myself at some point in the future so might keep the Heathkit in mind, seems a great value compared to buying something new with similar specs.

author: jitter
author_rank: Frequent Contributor
timestamp: October 05, 2016, 03:37:15 am
content: Quote from: setq on October 03, 2016, 03:55:58 pmIndeed, once you want to venture into the opamp world, a symmetrical supply is often needed and a dual tracking lab PSU will do that job nicely.Okay to have at home are two separate PSUs or a dual non-tracking PSU that you can wire in series to create a symmetrical power supply. Much nicer, though much more expensive, will be dual tracking PSUs that can be switched into series, parallel or independent and which (in tracking mode) only requires the operation of the master section to set both master and slave sections.This one caught my eye. It has sense terminals as well (but those are not needed unless you run high currents through long leads).http://www.ebay.co.uk/itm/THURLBY-30V-1A-DUAL-QUAD-MODE-POWER-SUPPLY-/381792453376?hash=item58e49a8300:g:q8IAAOSwvg9Xe7u7At work we use quite a few of these:http://www.ebay.co.uk/itm/GW-INSTEK-GPC-3030DQ-Power-Supply-30V-3A-/252567696524?hash=item3ace35348c:g:1pMAAOSwf-VWUvXsBut yeah... that price tag is a bit prohibitive.For less than half that price:http://www.ebay.co.uk/itm/Bench-Dual-Power-Supply-Adjustable-Output-0-30V-0-5A-x2-LCD-5V-3A-Linear-PSU-ITA-/262463004679?hash=item3d1c03a007:g:Hk0AAOSwbYZXVcusBut what you will start to dislike quickly in a quiet home environment are loud fans... A passively cooled PSU would always be highly recommended.

author: Brumby
author_rank: Unknown
timestamp: October 05, 2016, 04:09:00 am
content: Quote from: jitter on October 05, 2016, 03:37:15 amAside from fan noise (which I do not know anything about for these supplies) if you get one of these (as linked above), it will sit on your bench and pretty much become a permanent fixture. It provide all you need for many - if not most or all - of your projects as you learn and for many years to come.

author: Bukurat
author_rank: Regular Contributor
timestamp: October 05, 2016, 09:10:58 am
content: Quote from: Ross_mini on October 02, 2016, 06:12:02 pmBe careful with this. There are a lot of different versions of these on eBay and they all seem to suffer with the same fault in that the output voltage will spike when they are turned off, and sometimes when they are turned on. Once they are running they are ok, but don't tuning them on or off when connected to your circuit.

author: setq
author_rank: Frequent Contributor
timestamp: October 05, 2016, 09:32:41 am
content: I was going through my junk cupboard last night and found a powered breadboard that I forgot I had. Have stuck it in the buy/sell section on here - probably most needs for LTAoE:https://www.eevblog.com/forum/buysellwanted/fs-(uk)-global-specialities-powered-breadboard-bag-of-2n2907's/msg1041442/