EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: p.larner on September 28, 2023, 06:13:07 am
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has anyone got any plans for say a 0-20amp 0-60 ish volt diy psu with cc+cv,i have a huge transfo about 30cm square with a 47v tap,+some big diodes and caps etc,opamp or 723 based.?
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Wrong title...
THIS IS NOT HIGH VOLTAGE
High voltage = > 600..1 kV.
Mains = 120/240
j
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well over the normal 30volts!
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I don't consider it high voltage until you can get it to arc between wires
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well over the normal 30volts!
No. It's extra low voltage, which is defined as under 120VDC or 50VAC, but it still requires basic insulation, although no earth. In dry areas, voltages under 60VDC or 25AC don't need to be insulated. In damp areas, where there's a high risk of shock, all live conductors need to be insulated.
has anyone got any plans for say a 0-20amp 0-60 ish volt diy psu with cc+cv,i have a huge transfo about 30cm square with a 47v tap,+some big diodes and caps etc,opamp or 723 based.?
In another thread you mentioned you have a restricted budget, which makes this impractical, as it will be expensive.
Presumably you're talking about a linear, rather than switched mode supply? It would require a custom transformer, with many taps to keep power dissipation to a minimum.
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Defs: https://en.wikipedia.org/wiki/Extra-low_voltage
IEC voltage range AC RMS voltage (V) DC voltage (V) Defining risk
High voltage > 1,000 > 1,500 Electrical arcing
Low voltage 50 to 1,000 120 to 1,500 Electrical shock
Extra-low voltage < 50 < 120 Low risk
SELV: UL Safety Extra low Voltage 42.2 V peak OR less;
Here is a great REALLY high volktage site.....https://lod.org/
(Lighting on Demand, our old friend Greg LEYH)
Enjoy,
Jon
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has anyone got any plans for say a 0-20amp 0-60 ish volt diy psu with cc+cv,i have a huge transfo about 30cm square with a 47v tap,+some big diodes and caps etc,opamp or 723 based.?
That's high voltage for semiconductors ICs and they have thinned out for linear up there.
Parts like TL783 manage 125V, but they are the LM317 family with a 1.25V drop, so the ADJ pin needs to be driven to Vo-1.25, needing a high voltage opamp.
A TPS7A4001 is good to 100V and 50mA, so might work with a darlington output ?
Or, you could just choose a HV opamp like OPA455, OPA462 ? and simple darlington follower.
You will need a massive heatsink array of big output devices to manage 60V 20A peaks, that's 1200W !
Or, you could use the driver level shifting seen in Audio Power amps, to allow lower voltage opamps
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I look forward to seeing your cooling approach. Dissipating >1.2 kW worst case takes some doing.
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I look forward to seeing your cooling approach. Dissipating >1.2 kW worst case takes some doing.
Benta is correct, a better approach is maybe a multitap transformer with tap switching or perhaps a switch mode pre regulator followed by a linear post regulator or just switch mode.
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What application are you needing a linear supply with 20 amps?
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Following Benta's post:
If you really want to run this level of power in a linear supply, you should start the design process from the heat-sink/cooling end, then work backwards to the control circuit, etc.
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forgot to say the transfo has taps at the following voltages 1.5v 2v 2.6v 3.5v 6.2v 21v 26v 38v :i build ebike batterys so would be handy for charging those,also just would be a handy thing to have.,thought of using a chinese 0-30v 5a psu pcb kit as they are opamp based and have tap switching.maybe just change the current sense resistor?.
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forgot to say the transfo has taps at the following voltages 1.5v 2v 2.6v 3.5v 6.2v 21v 26v 38v :i build ebike batterys so would be handy for charging those,also just would be a handy thing to have.,thought of using a chinese 0-30v 5a psu pcb kit as they are opamp based and have tap switching.maybe just change the current sense resistor?.
If it's primarily for charging purposes then PWM/switchmode is the most economical way to go.
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you can base this circuit and evolve it ... from astron 50 50 amp psu ....
youcan make it variable down to 1.2volts and add an variable current etc ...
or this one too
Pyramid PS52KX
same mods can be done on this one too
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forgot to say the transfo has taps at the following voltages 1.5v 2v 2.6v 3.5v 6.2v 21v 26v 38v :i build ebike batterys so would be handy for charging those,also just would be a handy thing to have.,thought of using a chinese 0-30v 5a psu pcb kit as they are opamp based and have tap switching.maybe just change the current sense resistor?.
You are better to pick one rated to more current, if you want to use all the ability of the transformer.
Ones like this claim 60V 20A - but are switching. If you just want to charge batteries, it should be fine ?
https://www.aliexpress.com/item/1005005558425514.html (https://www.aliexpress.com/item/1005005558425514.html)
or this claims 25A, looks to have better tunnel cooling.
https://www.aliexpress.com/item/1005005639051641.html (https://www.aliexpress.com/item/1005005639051641.html)
this one claims 50A
https://www.aliexpress.com/item/1005005884099336.html (https://www.aliexpress.com/item/1005005884099336.html)
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i dont realy need one badly,its just i have this monster transformer that i payed a fiver for at a hamfest sitting on my floor and thought it was time i got round to building something usefull with it couldnt pass on it for five pounds,orth more than that for scrap copper i would think.
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We needed 60 to 90V at 15 amps peak, so just ordered a Korad KWR103 (60V at 15 amps) to go with our KWR102 (30V at 30 amps). The KWR103 is only 60 volts tho, so for higher output voltage we'll need to stack them and see how this works. This is for receptive pulsed applications, not continuous load.
Best,