Hello All!
Story; I have recently found this gigantic 300W, 230 to 110 volts Isolating transformer from a dumped soda-pop automat I found in the forest (of all places!)
This I would like to use in a powerfull universal Power supply to have in my, ahem, 'test lab' 🙂
I don't have much experience in large powerful PSU's so I was wondering if anyone have got any ideas / shematics or something to witch I could put the transformer to good use.
I am thinking about adjustible output voltage... 1-50 volts for example. Nothing advanced. Though, a current limiting adjustment thingy is nice to have around. maybe 0-5A or something....
Any ideas are welcome....
Stig
Story; I have recently found this gigantic 300W, 230 to 110 volts Isolating transformer from a dumped soda-pop automat I found in the forest (of all places!)
This I would like to use in a powerfull universal Power supply to have in my, ahem, 'test lab' 🙂
I don't have much experience in large powerful PSU's so I was wondering if anyone have got any ideas / shematics or something to witch I could put the transformer to good use.
I am thinking about adjustible output voltage... 1-50 volts for example. Nothing advanced. Though, a current limiting adjustment thingy is nice to have around. maybe 0-5A or something....
Any ideas are welcome....
Stig
As far as I see, given the high secondary voltage of 110 VAC, you would get roughly 150 VDC after rectifiers. This means that you have to get rid of 100 VDC at the current you want which means something like 250 W if the maximum current is around 2.5 A (which it is for 300 VA at 110 VAC I think. That makes the PSU kinda hot. I would find another transformer and use this one for something else...it would probably be cheaper (hint: check what people think about cost for heating houses with heatsinks here).
/UrSv
/UrSv
Tranformer
230 V winding connected to 115 AC will give about 55V AC out which is about 75 V DC which could be used for 50V regulated supply with big heatsink. Switching supply....... I don't think so.
230 V winding connected to 115 AC will give about 55V AC out which is about 75 V DC which could be used for 50V regulated supply with big heatsink. Switching supply....... I don't think so.
hmmm, well, we use 230V AC here where I come from....
It is obviously possible to open the tranny by removing some screws, so if the windings is not dipped in lack or something it may be possible to wind off some turns on the secundary to give around 50-60V AC out.... this will improve current-handling too!! Will investigate this further tomorrow.
Stig
It is obviously possible to open the tranny by removing some screws, so if the windings is not dipped in lack or something it may be possible to wind off some turns on the secundary to give around 50-60V AC out.... this will improve current-handling too!! Will investigate this further tomorrow.
Stig
dont count on it improving current handling and you'd have to remove an awful lot to drop the secondary by that much ....
Harry,
Basic switching supplies do not have to be that complex and can end up very well regulated indeed.
Harry,
Basic switching supplies do not have to be that complex and can end up very well regulated indeed.
having thought more about it, that power transformer would not be very useful in a simple switching supply either.
Opened up the tranny today, despite AudioFreaks advice....
Was easy, infact, the two windings (prim. and sec.) was completely sectioned, so the only hard work was to remove and re-install the E and I's... took some time.
Winded of some 60 turns I think, forgot to count :-( Added a smaller winding to be used in series if I had wound off too much.
When finished I wrapped the windings with plumbers teflon tape and put the E, I's back. (got 5 leftovers I couldnt get in...)
Anyways, I've now got a 57V AC out and a 19V AC out. Gives around 80 volts of DC... still a bit high or what?
Stig
Was easy, infact, the two windings (prim. and sec.) was completely sectioned, so the only hard work was to remove and re-install the E and I's... took some time.
Winded of some 60 turns I think, forgot to count :-( Added a smaller winding to be used in series if I had wound off too much.
When finished I wrapped the windings with plumbers teflon tape and put the E, I's back. (got 5 leftovers I couldnt get in...)
Anyways, I've now got a 57V AC out and a 19V AC out. Gives around 80 volts of DC... still a bit high or what?
Stig
that could be of some use .... use the lower voltage winding for low voltage and the high voltage winding for higher voltages but the note still applies .... be careful of the current requirements you place on the transformer.
Yeah, I'll fuse it ofcourse.
How about using f.ex. a LM 723 to control a transistor, f.ex a MJ15001 (140V, 15A max).... I can use the 19V winding to power the LM 723...
Or what about putting f.ex. three LT 350 in series, so that I don't go over the max Voltage rating?
Maybe using a LM317 HV to control a transistor?
I'm thinking like this. Anyone got any ideas / experiences?
Stig
How about using f.ex. a LM 723 to control a transistor, f.ex a MJ15001 (140V, 15A max).... I can use the 19V winding to power the LM 723...
Or what about putting f.ex. three LT 350 in series, so that I don't go over the max Voltage rating?
Maybe using a LM317 HV to control a transistor?
I'm thinking like this. Anyone got any ideas / experiences?
Stig
any of the LM317's work well and as long as you dont directly reference then to ground, you can regulate many 100's of volts @ the output.
they use floating electronics so you dont have to reference it 2 real ground so long as you provide it with a stable reference but given that this is only 5v, yes you would reference it to ground as per the data sheet
so, how can I use a regulator like LT350 to control around 80V? (35 volts max...)
Can it be done? I've seen they've been used in paralell to enhance current capability, can they be conected in series with a common adjusting point to enhance voltage handling?
stig
Can it be done? I've seen they've been used in paralell to enhance current capability, can they be conected in series with a common adjusting point to enhance voltage handling?
stig
I've posted a suggestion for a circuit. I HAVE NOT TESTED THIS!!!
Any comments? Caps are based on what I have in my junk-box.
Any comments? Caps are based on what I have in my junk-box.
An externally hosted image should be here but it was not working when we last tested it.
Over 35V with an LM317
Note first, there is a higher voltage LM317 -- the HVK, but this won't get you to 80V. To regulate a voltage above the max permitted by the regulator you use a series of zener diodes in the "adjust leg" to bring the base voltage up to the level you desire. You must also protect the LM317 from "overvoltage" with a zener from the adjust leg. The description gets a little wordy, so look at this link of a 290 Volt regulator I used with a much doctor-ed up Fairchild 255a:
http://www.tech-diy.com/fairchild_255a.htm
it's not pretty, but it works and hasn't blown up. I used a BU208 transistor as that's what I had in the junk box. For your purposes, you would use zeners to get you in the vicinity of 80V.
btw, you can get an LM317 regulator down to "0" volts by biasing the adjust arm with approximately -1.25 volts.
Note first, there is a higher voltage LM317 -- the HVK, but this won't get you to 80V. To regulate a voltage above the max permitted by the regulator you use a series of zener diodes in the "adjust leg" to bring the base voltage up to the level you desire. You must also protect the LM317 from "overvoltage" with a zener from the adjust leg. The description gets a little wordy, so look at this link of a 290 Volt regulator I used with a much doctor-ed up Fairchild 255a:
http://www.tech-diy.com/fairchild_255a.htm
it's not pretty, but it works and hasn't blown up. I used a BU208 transistor as that's what I had in the junk box. For your purposes, you would use zeners to get you in the vicinity of 80V.
btw, you can get an LM317 regulator down to "0" volts by biasing the adjust arm with approximately -1.25 volts.
Just a note, when i said 5V i was thinking about another thread ...
for the higher voltage section you will indeed need to use a reference point other than ground .... also, you did not mention what gauge wire you used on the lower voltage winding that you added....
for the higher voltage section you will indeed need to use a reference point other than ground .... also, you did not mention what gauge wire you used on the lower voltage winding that you added....
Oooops, rectifiers wrong way in the schematic.
To the second winding I used the wire I wounded off from the first winding. 1mm diameter + isolation.
The LM317 HV can source 0,5A, at 60V. The TL783 takes 0,7A at 125volts. Quite suitable me thinks... That means I can reference it to ground like in the schematic, yes?
One thing though. The TL783 is rated to 15-700mA. What does that mean? Does the regulator consume 15mA, or do I have to have some bleeders after it to have a constant 15mA running through it?
stigla
To the second winding I used the wire I wounded off from the first winding. 1mm diameter + isolation.
The LM317 HV can source 0,5A, at 60V. The TL783 takes 0,7A at 125volts. Quite suitable me thinks... That means I can reference it to ground like in the schematic, yes?
One thing though. The TL783 is rated to 15-700mA. What does that mean? Does the regulator consume 15mA, or do I have to have some bleeders after it to have a constant 15mA running through it?
stigla
hv regulators
both the LM317 and the TL783 have to be derated when there is a large input to output differential. the last time I looked at the application notes at National Semi they indicated that the regulator needs a minimum base current to "regulate" at the specified level of ripple -- I haven't found this to be a problem in any of the applications where I use an LM317.
I was interested to see on TI's website the use of the TL783 as a high voltage amplifier by modulating the "adjust" pin. Do we have the kernel of an electrostatic speaker amp here? Jack
both the LM317 and the TL783 have to be derated when there is a large input to output differential. the last time I looked at the application notes at National Semi they indicated that the regulator needs a minimum base current to "regulate" at the specified level of ripple -- I haven't found this to be a problem in any of the applications where I use an LM317.
I was interested to see on TI's website the use of the TL783 as a high voltage amplifier by modulating the "adjust" pin. Do we have the kernel of an electrostatic speaker amp here? Jack
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