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DIY power supply/function generator

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alm:
All of the mentioned solutions (including the L200 with the solution Anders mentioned) can use a shunt separate from the pot.

Most solutions will need some kind of negative voltage below the output ground to regulate all the way to 0V (gotta get that base at 0V-Vbe). I wonder how the MC1466L got around this, internal voltage inverter like the MAX232? I'm not familiar with the MC1466L, apparently it's better in some aspects, but I'm not a big fan of using obsolete parts in new designs unless there's really no (good) alternative. It's bad enough to have to chase down obsolete parts to repair existing stuff, no need to create these problems in advance.

One solution to limit dissipation used before the introduction of switching power supplies was a triac pre-regulator before the power transformer. This is simpler than a real switcher, but probably not worth the effort these days. You do need to filter out the noise if low noise output is an issue.

A more basic solution to limit dissipation, especially if you want a large voltage range (eg. 0-30V), is to use a switchable voltage doubler (used in some ELV designs) or a transformer with two secondary windings and switch the second winding. A (solid-state) relay is used to switch the extra leg. The former requires double the capacitance (and some diodes), the latter a transformer with two secondaries and two extra diodes (but if you buy new, you don't usually pay much extra for that). This lets you halve the input voltage once you get below half the max. output voltage or so, and saves you 50% on dissipation with worst case scenario (dead short, the pass transistors have to dissipate 99.9% of the voltage at max. current).

angelo:
UPDATE:

The last part I needed has finally shipped from China so in approx 7 days I will photo-document my progress. I will be building the function generator and power supply separately for noise control.

the function generator will use: XR2206 IC, with pots for amplitude and frequency adjustment (0-12v, 2-2Mhz) and a switch for triangle, square, sine waveforms. it will have banana jack connectors and a BNC output.

the power supply will use: 2x LM150 and 7805, it will have voltage regulation from 1.25v to 20v and amperage regulation to 2.5A. it will have banana jacks for the adjustable output as well as a second set for the 5v output. the amperage/voltage regulation will have a switch to control what is being regulated and I have two LCD's displaying the supplied voltage and amperage.

Both will be powered over a 2.1' barrel jack supplied by a 24v 3A laptop power brick with built in safeguards and circuit protection.

I will keep you posted.

If anyone knows any good books I could check out that they used from experience, not just suggestions from the net, I would be very grateful

thanks again
--

Angelo

saturation:
You have the LM150?  I read they are discontinued for some years, the LM350 is an upgrade, with similar specs.  Keep us posted, and enjoy.

Good Books: as always, Horowitz and Hill, if you had to own but one.


--- Quote from: angelo on May 14, 2010, 04:53:38 pm ---UPDATE:

The last part I needed has finally shipped from China so in approx 7 days I will photo-document my progress. I will be building the function generator and power supply separately for noise control.

the function generator will use: XR2206 IC, with pots for amplitude and frequency adjustment (0-12v, 2-2Mhz) and a switch for triangle, square, sine waveforms. it will have banana jack connectors and a BNC output.

the power supply will use: 2x LM150 and 7805, it will have voltage regulation from 1.25v to 20v and amperage regulation to 2.5A. it will have banana jacks for the adjustable output as well as a second set for the 5v output. the amperage/voltage regulation will have a switch to control what is being regulated and I have two LCD's displaying the supplied voltage and amperage.

Both will be powered over a 2.1' barrel jack supplied by a 24v 3A laptop power brick with built in safeguards and circuit protection.

I will keep you posted.

If anyone knows any good books I could check out that they used from experience, not just suggestions from the net, I would be very grateful

thanks again
--

Angelo

--- End quote ---

kc1980:
I've been working on my design (as time permits), but I realized that I shouldn't hijack Angelo's thread.  I will create a separate post when I finish tracking down the sources of oscillations.  Grrrr.... :'(

BTW, Angelo - I look forward to seeing what you have going on.  It's always nice to see other people's projects in development.

Peace,
Ken

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