Looking for least expensive variable 12VDC 8A power supply

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Macro_Cosmos
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by Macro_Cosmos »

The Riden RD6006 is a very good option, around $90. It uses a power supply commonly found in desktop computers.

Otherwise, as Pau said, you can get a 100W tungsten halogen power supply for microscopes from sites such as eBay, I have sold an Olympus one for $30. Far better than the $15 ones with questionable electronics.

MeanWell is a decent brand, their power supplies are usually $25-$30. Get the industrial grade. The medical grade ones are more expensive and the only difference is output isolation.

Chris S.
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by Chris S. »

Macro_Cosmos wrote:
Sun Feb 13, 2022 3:38 pm
The Riden RD6006 is a very good option, around $90. It uses a power supply commonly found in desktop computers.
Looking up "Riden RD6006" led me to this video: RIDEN RD6006 Power Supply Kit with WiFi control | Android App by the YouTuber "Electonoobs."

Sure looks cool! If I get it right, the Riden RD6006 is a controller/display unit, to which one must add things like an actual power supply and project box. Watching this video, I was impressed at this controller's features, such as computer/smartphone control and data capture.

On the other hand, this controller looks--to my eye at least--very complicated to use. I think I'd want a printed copy of the manual on my bench, and would need to refer to it uncomfortably often.

Granted, complexity is often the price we pay for capability.

But my sense is "Ack! Let me stay with my simple, intuitive bench power supplies for now, and consider this only if I ever need the advanced features."

Do I have it wrong?

--Chris S.

Macro_Cosmos
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by Macro_Cosmos »

Chris S. wrote:
Sun Feb 13, 2022 10:57 pm
On the other hand, this controller looks--to my eye at least--very complicated to use. I think I'd want a printed copy of the manual on my bench, and would need to refer to it uncomfortably often.

Granted, complexity is often the price we pay for capability.

But my sense is "Ack! Let me stay with my simple, intuitive bench power supplies for now, and consider this only if I ever need the advanced features."
There are different options. The display kit is $35 or so, the case is another $20, then there is an option to purchase the fully installed unit for around $80. The power supplies are standard, if you work in an office with access to e-waste dumpsters or have an old surplus PC lying around, they are free, so it is $60 for a programmable bench power supply -- why pay $50 for a brick? Otherwise the fully installed ones are around $80-$95, I paid $90 for mine, included shipping I believe.

FYI, even though I sold my Olympus 100W tungsten halogen power supply for $30, local shipping was $35, it is quite large and very heavy for what it is. I still recommend this route since it is simple and safe. There is always a chance that the salvaged PSU one's going to use for the unit is a dud and does silly things.

It is very easy to use. I-Set, use dial to set a current, V-Set, ditto for voltage, done? Press "on/off". All the other buttons are for memory and some measurement features I can personally care less about. Three buttons and a dial is all I need. I also use it to charge various batteries, this requires a little bit of knowledge or reading two articles, saved a lot on battery chargers.

brettpim
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by brettpim »

Thanks everyone for all these great ideas of affordable power supplies! Shipping is a significant cost factor to moving around all the used items in the world that other people would use. The Riden RD6006 is an impressive tool. It certainly has a price point very favourable to the $300 I paid for my Circuit-Test PSC-520.

Macro_Cosmos
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by Macro_Cosmos »

brettpim wrote:
Thu Feb 17, 2022 7:59 am
Thanks everyone for all these great ideas of affordable power supplies! Shipping is a significant cost factor to moving around all the used items in the world that other people would use. The Riden RD6006 is an impressive tool. It certainly has a price point very favourable to the $300 I paid for my Circuit-Test PSC-520.
I am sorry to hear that, is it made in China? What an absolute rip off.
It looks like one of the many white labelled units.

$300 gets you a higher end powerful Rigol unit, a pretty reputable brand. It has all kinds of fancy features.
https://www.ebay.com/itm/174958124400?h ... SwXPVhVI1V

brettpim
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by brettpim »

A Meanwell LRS-150-12 with a 12-24V 30A PWM dimmer works perfectly to power my 12V 100W halogen light. Total price of two components was \approx US$30.00 including shipping which is not bad! Thanks for the help and good suggestions.

brettpim
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by brettpim »

I thought I would show the first unit I built. In the end I went with using the 12V line on an old power supply because it had a fan built in and also did not have the 120V terminals exposed like the Meanwell LRS-150-12. Work has a ton of computer power supplies and gave me an old Seasonic SS-300TFX with a 24 pin Molex output. This is a pretty small unit which is nice. I added a wire-wound resistor as a load on the 5V line, put a switch on the PS-On line and an LED on the Power good line. I ran the 12V line to my PWM and ran its output to two binding posts. It is not pretty but it works pretty well. I found the following two pages useful: Desktop Power Supply from a PC and Convert an ATX Computer Supply to a Bench Power Supply.
top_view.jpg
angle_view.jpg
powering_light.jpg

PeteM
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by PeteM »

This might be another possibility:

https://www.amazon.com/gp/product/B0899 ... UTF8&psc=1

I recently installed one of these to fit inside the base of a Nikon Microphot, which uses a 100 watt halogen lamp. It's fully dimmable with an ordinary dimmer. Burned it in for 30 minutes and then installed it inside the base with thermal paste. It's been running OK for maybe 12 hours since - with one glitch. I fused the scope for 3 amps, fast blow, 120volts. There are two power supplies on that fuse. This one and a tiny wall wart tucked inside to run a small DC gear motor. I suspect the inrush current, not fully limited by the power supply, made that fuse unhappy. The replacement seems fine with maybe 8 hours on it. Might be I should fuse it more like 2 amps, slow blow.

It could well be that this will have early mortality. But so far the power supply's current limiter seems to tolerate the inrush current, the lamp comes on under a second, and the variable feature works fine.

One reason to install this supply, other than that it would fit, is that I intend to try a UV LED in the Epi position of the scope - and being a constant current source I can run either halogen or LED on the same supply. Anyhow, so far so good.

jfiresto
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by jfiresto »

PeteM wrote:
Sat Apr 16, 2022 9:36 am
... Might be I should fuse it more like 2 amps, slow blow....
That is what I might try at 120VAC. A 20–60A inrush current will eventually blow a fast acting fuse.
– John

brettpim
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by brettpim »

I tried building a second power supply from a API1PC36 from a G4 Macintosh (using Daniel Haertle's similar project description). If I connect the 12V 100W halogen directly to the power supply it works fine as its 12V line can handle up to 16A. If I include the 12-24V 30A PWM dimmer between the power supply and the lamp, the power supply switches itself off if I start the power supply with the dimmer set to anything less than approximately 95%. If I start the power supply with the dimmer at or almost at full, then the power supply does not switch off until I lower the PWM's dial. I have had some success when I put additional loads on the 3.3V line. I have asked on Electrical Engineering Stack Exchange for help diagnosing and fixing problem.
Last edited by brettpim on Sat Nov 26, 2022 3:25 pm, edited 1 time in total.

brettpim
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by brettpim »

I have found that there are two solutions to getting the PWM to dim the 12V halogen bulb with the API1PC36 power supply: you can add more load to the power supply's sense line; or you can add fairly large capacitance in parallel to the input side of the PWM. The set up and solutions are described in my question and answers on Stack Exchange.

blekenbleu
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by blekenbleu »

brettpim wrote:
Thu Apr 14, 2022 6:39 pm
I thought I would show the first unit I built.
To address the inrush current issue, consider a dimmer pot with power switch,
so power turns on with minimum PWM, as was done on many microscopes.
This dimmer has an external pot that could be swapped for one with a switch:
https://www.ebay.com/itm/225170159915
... perhaps the pot on your dimmer could similarly be replaced.
Metaphot, Optiphot 1, 66; AO 10, 120, and EPIStar 2571
https://blekenbleu.github.io/microscope

brettpim
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by brettpim »

Thanks for this idea and link, blekenbleu. This seems like a good inexpensive option for a microscope.
brett

blekenbleu
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Re: Looking for least expensive variable 12VDC 8A power supply

Post by blekenbleu »

brettpim wrote:
Sat Nov 26, 2022 7:16 pm
This seems like a good inexpensive option for a microscope.
JameCo offers a decent selection of switched potentiometers:
https://www.jameco.com/c/Potentiometer.html#/rq:switch
Metaphot, Optiphot 1, 66; AO 10, 120, and EPIStar 2571
https://blekenbleu.github.io/microscope

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