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hot_chmock
Joined: 22 Jun 2001
Posts: 161
Location: Where it is nice
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 15 Mar 2003 21:49 Electronic Power supply load |
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Hi,
I need to build an electronic power supply load for testing purpose.
Any information, link or diagram is welcome.
Thanks,
hc
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flatulent
Joined: 19 Jul 2002
Posts: 4875
Helped: 324
Location: Middle Earth
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15 Mar 2003 22:02 high power current sink |
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The usual method is to make a high power current sink. Start with a power transistor with its emitter or source connected to a small resistor which is connected to ground.
have an op amp -input connected to the resistor and its output connected to the base or gate. Putting a voltage on the other op amp input will control the current drawn.
This other voltage can come from a manual variable resistor voltag divider or a DAC run by a computer if you want dynamic measruements.
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15 Mar 2003 22:02 Ads |
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Jayson
Joined: 08 Oct 2001
Posts: 460
Helped: 17
Location: Brazil
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| 15 Mar 2003 23:58 |
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I wonder do those expensive electronic loads (ProDigit, Kikusui) also use the method Flatulent described? I've often wondered why they're so expensive.
Anyway, these circuit ideas are really useful. does anyone know of any online schematic respositories that have these types of circuits and explanations of how they work? All books out there deal with opamps and transistors, but in seperate chapters, never how to combine them.
Another interesting circuit is the MOSFET switch using two MOSFETs, again no books I've seen have these ready made recipes. An online collection would be a really nice thing to have reference to.
- Jayson
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flatulent
Joined: 19 Jul 2002
Posts: 4875
Helped: 324
Location: Middle Earth
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16 Mar 2003 2:53 simple hobby circuit |
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What I explained is simple enough for a hobby use. The commercial devices have much more performance and exceed ordinary hobby needs.
For instance, they can draw current with 0V or so across them. They can measure the output impedance of the supply at different frequencies.
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billano786
Joined: 26 Apr 2001
Posts: 370
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| 16 Mar 2003 17:17 |
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Here is something useful.
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SAR
Joined: 25 Sep 2002
Posts: 152
Helped: 4
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16 Mar 2003 19:34 Load |
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Try here:
http://www.webx.dk/oz2cpu/radios/dc-load.htm
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Eternauta
Joined: 09 Oct 2003
Posts: 24
Helped: 1
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13 Mar 2004 9:46 Re: Electronic Power supply load |
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In the attached file the schematic of an electronic load for PSU testing. It's interesting the possibility to switch between fixed ampere consumption and fixed Ohm load. It's from a kit that an hobby magazine sell in Italy: "Nuova Elettronica".
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aslm
Joined: 03 May 2002
Posts: 125
Helped: 5
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15 Mar 2004 20:18 Re: Electronic Power supply load |
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Hi, needed something simular a couple of month ago and built a load with opamps and power mosfets simular to the one described in the link two posts up. Works fine, a bit unstable, but with som extra filtering It has been to great help for my SMPS project.
re Me
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AL0117
Joined: 25 Jul 2003
Posts: 237
Helped: 8
Location: dracu-la-nd
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16 Mar 2004 8:51 Re: Electronic Power supply load |
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Hi,
Check out the TI (formerly Unitrode) design note "Adjustable Electronic Load for Low Voltage DC Applications".
hxxp://www-s.ti.com/sc/psheets/slua045/slua045.pdf
rgds, Al
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