| The Shop > Electronics & IC Programing |
| Digital oscilloscope project/kit |
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| RobWilson:
--- Quote from: John Swift on January 06, 2016, 06:26:16 PM ---Hi Rob just got back from the Everton v Manchester City match (we won 2-1) no I didn't build the LED scope I built a Vellerman LCD scope about 12 years ago I've not used it for a while it needs the 6 AA nicads replacing John --- End quote --- Hi John That looks a canny project , shame the kit is no longer available . I dont do football I prefer things with two wheels and an engine :thumbup: ,,,,,,,,,,,,,,the wife is a big Toon sports direct supporter :lol: Rob |
| RobWilson:
While on the subject of PSU , I bought the 0-30v PSU kit and it needs a mains transformer . 240v to 24v 3 amp max Would this one from ESR do the job p# 311-312 https://www.esr.co.uk/electronics/products/frame_transformers.htm Cheers Rob |
| RobWilson:
--- Quote from: wheeltapper on January 07, 2016, 10:49:12 AM ---Yippee. I think I've fixed it. the first thing I did was reflow R18, that fixed the AC problem. I just reflowed pins 1 to 7 on IC U2 and all the voltages are correct now. PHEW! thanks for the help. Roy. --- End quote --- Good to hear you got it sorted Roy :thumbup: Rob |
| RobWilson:
--- Quote from: John Rudd on January 09, 2016, 04:16:00 PM ---If the BG psu is the one Rob referred to, it has some flaws..... --- End quote --- John while searching the Banggood site I came across the PSU for the signal generator , a tad better than the suggested one in the manual , I will still make the suggested one as I have the parts . Anyway http://www.banggood.com/DIY-USB-Boost-Single-Turn-Dual-Power-Module-Linear-Regulators-Multiple-Output-Power-Kit-p-1022517.html , on order . Input voltage: 5-24V DC Output voltage: + 12V, -12V, + 5V, -5V , +3.3V. Output current: 300mA (per channel) Rob |
| John Rudd:
Rob, There ara number of issues with that power supply kit, not least of all tha fact that a transformer with a 24 v ac secondary is going to give something like 36 v dc across C1... Plus there is around 5v across D7.... This is totaling some 40 plus volts powering the three op amps...These are TLO81's with a maximum supply of 36 across their supply terminals....Result? :zap: Thecanswer to this problem is use op amps with a higher operating voltage or use a transformer with a lower secondary voltage.... To answer your transformer question, the voltage is too high, see the above....and the current rating too low to expect 3 amps from the power supply..... If the shortcomings of the design are overcome, then a transformer with at least a va rating of 100 watts is needed....( dont forget the power supply is 'supposed ' to be good for 30 v x 3 A or 90 watts...realistically a 120 watt rated transformer is needed..... If you want to run the power supply as designed, then go for a transformer with a lower secondary voltage.....but then that cant becallowed to go too low else the Negative voltage rail charge pump circuit wont give the designed voltage.....(C2,C3,R2 R3, D5/D6) |
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