power supply circuit

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david753
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power supply circuit

Post by david753 » Fri Mar 18, 2005 2:36 pm

Does anyone have power supply circuit that has 0~+/-30v dual output ports function and can be adjusted in voltage and current output?
I'd like to implement one that just for my hobby.
Please offer it as my reference.
Appreciated.

Mike
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Re: power supply circuit

Post by Mike » Fri Mar 18, 2005 3:00 pm

I can get you a circuit for +/-1.5VDC to +/-35VDC, but no varible current option.<p>It can be done, but requires more parts. Why do you need it anyway? for most things, it will only use however much current it needs

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Edd
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Re: power supply circuit

Post by Edd » Sat Mar 19, 2005 2:32 pm

Looking thru my archive of circuits , hard to beat this one , best part is only common generic parts being used . Has the lower voltage level settability that you requested as well as constant current limiting capability. Duplicate to make a dual supply.
Reference the second supply down of the series:
http://ourworld.compuserve.com/homepage ... tm#ps6.gif <p>73's de Edd
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;) ;)<p>[ March 21, 2005: Message edited by: Edd Whatley ]</p>

Ron H
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Re: power supply circuit

Post by Ron H » Sat Mar 19, 2005 4:15 pm

Edd, that's a good power supply circuit, but the current limiting doesn't fold back. It simply limits to a constant current whose value is adjustable.

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Edd
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Re: power supply circuit

Post by Edd » Sun Mar 20, 2005 2:31 pm

Hey Ron…Why ‘soitanly...dat do be rite… I had 3 circuits in mind and was thinking of one like that at a rushed posting time. One was with fold back , but the one submitted was decided upon by virtue of the capability of switch/ diminishment of the PS raw unreg DC level to ease the strain on the pass regulator xstr while being used at low voltage levels. Also the use of common generic parts…with no exotica…MHF88a67-32pds IC’s being required!<p>And the reason I use one, is that if I have a designed circuit that I am about to power up and, being knowledgeable of the expected current consumption. I can set the current threshold at that limit such that no more that is consumed by the circuit and not ending up with a major parts
crashing otherwise.<p>73’s de Edd
[email protected] ..….....(Interstellar~~~~Warp~~~Speed)
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;) ;)<p>[ March 20, 2005: Message edited by: Edd Whatley ]</p>

Bernius1
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Re: power supply circuit

Post by Bernius1 » Tue Mar 22, 2005 6:09 am

Edd, I've seen supply circuits that reverse polarity. Take a look at Image this image. (This is the direct link
http://img8.exs.cx/img8/5755/polarity3eb.jpg ) "thanks to imageshack" . Assuming that this is a square wave out of a PIC at TTL levels, will the output at the top of the inductor be negative , relative to ground ? It looks like a charge pump to me. The upper diode looks like it'll only allow the coil to backflow into the supply cap. I thought it wouldn't be necessary, but without it the output will see positive voltage. My problem in component choice lies in the resistors, I think, because the resistor below the LED will limit output current by limiting the 'charging' of the ground plane. The resistor under the inductor is the key, though, because it will A) affect the voltage built by the dI/dt of the inductor, and B)has a time constant with the charging cap, yielding a tough RLC circuit. Any thoughts ? I KNOW that a PIC's output is mA's . I used a large value cap for higher current. Assume PIC out through TIP41 / 3055 power x-istor.
Can't we end all posts with a comical quip?

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Edd
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Re: power supply circuit

Post by Edd » Tue Mar 22, 2005 6:22 pm

Didn’t notice you post ‘til just now they have a way of sliding down the listings in a hurry at times. And if that circuit is driven with the 1 khz drive freq shown, the inductor will be just like a shorted wire at that frequency but will have that negative voltage rectified by the diode shown, naturally with a some filtering also needed. Also the ground return is hampered in the manner shown. In a typical charge pump utilization a second diode closes the loop to ground.
Typical example of what I am used to seeing……but, with high freq drive:
Image<p>The LED hints of merely being an activity indicator and the inductor not being in a ringing mode functon, since you are using a slow 1 khz operating freq which would not be conducive of ringing that value of an inductor with any success. Also I can’t see a PIC’s output level even starting to tolerate that 1000uf to be dumped into, needs to be, at the minimum, feeding into the bases of an NPN/PNP pair in a series totem pole arrangement with the cap fed from their midpoint, or further made into a darlington arrangement with your suggested TIP NPN/PNP pair.
If you were wanting to use the inductor in a ringing mode and recover its inductive flyback voltage
The optimal operational drive range would be up in the 20-50-200 khz range, as well as the circuit being different. (Far better to have 200 men dumping a water pail into a storage reservoir rather than just one in a same time period.)<p>73’s de Edd
[email protected] ..….....(Interstellar~~~~Warp~~~Speed)
[email protected]….......(Firewalled-Spam*Cookies*Crumbs)<p>HEY! Where’s our: Can't we end all posts with a comical quip?...quip
....or did that just get caught on your auto-signature function and U can’t get it off ?<p>Actually….the fight that we had last night was my fault, seems my wife asked me what was on the TV and I said dust.

Bernius1
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Re: power supply circuit

Post by Bernius1 » Wed Mar 23, 2005 6:00 am

Edd, I know the values are way out. The ckt was a 30-second cut & paste. A PIC , or even 555 will have to switch a higher freq MOSFET. I really like your ckt, except that it's more like a reference supply for a sensor, than a secondary reversed power supply (current-wise). I did want to use the flyback voltage. That's why I mentioned the resistor adjacent to the coil. Too high ( or unloaded supply) and I'll get -20V or more. Most regulators today either clip the wave, or dissipate extra current. So SOME part of the source is wasted. For an op-amp test bench, I'd like a fully variable +\- supply, preferrably something PIC controlled. Think, the first PIC ckt is usually a blinking LED. Replace LED with two ckt's, one 78L05, and a 79L05 driven by your inverter, and you'll have a proportionally variable supply, where increases in positive supply voltage will yield an equal increase in negative supply. Then all I'll need is two hi-value resistors near the amps (maybe with small caps) to prevent localized floating in the ground. AND, if I do it right, a 12V supply should max-out at +\- 11V , with lower current. BTW, will you be fixing or replacing the 'dusty TV'??
Can't we end all posts with a comical quip?

labview1958
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Re: power supply circuit

Post by labview1958 » Tue Apr 05, 2005 8:35 am

Hi,<p>I just join. I am trying to design a circuit to control the speed of a DC motor using a square wave generated by my PC using labview programing. My PC has a NI-DAQ 6025E card. Is that possible? I would be sending my circuit in the next mail.

labview1958
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Re: power supply circuit

Post by labview1958 » Tue Apr 05, 2005 9:00 am

I am going to attempt to paste the circuit here. Hope it works!<p> Sorry cannot paste! Next time!

david753
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Re: power supply circuit

Post by david753 » Tue Apr 05, 2005 12:58 pm

http://ourworld.compuserve.com/homepage ... tm#ps6.gif
In this circuit, in second side, there are 2 sets output, but it is hard to buy it in market.
Is it possible to buy a transform that only has 12.6, CT, -12.6 output?
but, there will be 2 sets of ground in the system when switching to the 36v position.
Can I do that?

labview1958
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Re: power supply circuit

Post by labview1958 » Tue Apr 12, 2005 6:06 am

I have a source that generates a TTL signal. I can vary the DUTY cycle. Can I use this to control the speed of a DC motor by just using ONE TIP41 power transistor and resisor with a 40 V power supply. I need to control the speed of the DC motor only one way.

Ron H
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Re: power supply circuit

Post by Ron H » Tue Apr 12, 2005 6:50 am

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by labview1958:
I have a source that generates a TTL signal. I can vary the DUTY cycle. Can I use this to control the speed of a DC motor by just using ONE TIP41 power transistor and resisor with a 40 V power supply. I need to control the speed of the DC motor only one way.<hr></blockquote><p>Labview, you are inadvertently trying to hijack this thread. You need to go to the top level of the General Forum and start a new topic.<p>[ April 12, 2005: Message edited by: RonH ]</p>

labview1958
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Re: power supply circuit

Post by labview1958 » Mon Apr 25, 2005 2:51 am

Anyone knows how to post JPG image?

dyarker
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Re: power supply circuit

Post by dyarker » Mon Apr 25, 2005 8:38 am

You need to put the image on a web server somewhere, enter the URL in the box that comes up when you click the image button.<p>The N&V forum server does not store images, so you can not paste them here.<p>If you do not have a web site, there are free image store servers out there. (I have a web site, so I didn't remember them when they were listed here before.)<p>Cheers,<p>[ April 25, 2005: Message edited by: Dale Y ]</p>
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