Cheap DC-DC converters for over 60v input.

[fechter]

There don't seem to be many dc-dc converters out there that will handle input voltages higher than 60v. Building one from a "Simple Switcher" chip also limits you to under 60v input.

I had a few switching power supplies that were pulled out from medical equipment in my office, so I tried hooking one up to my bench power supply (actually two bench supplies in series to get enough voltage). At 60vdc input, the thing worked great! It's spec'd to operate from 84 to 240vac input, but since the input goes through a bridge rectifier, dc input works fine. It worked OK on 60v, but crapped out somewhere around 50v, so it won't run off 48v.

The one I tested is
http://www.slpower.com/Upload/Technical ... GSM28G.pdf

I've seen a wide variety of similar switching power supplies at
http://www.allelectronics.com/cgi-bin/c ... plies.html

I think most of the models with a wide input range should work for 60v and above. Many of them are under $10. Perfect for running 10-20w headlights.

Another cool feature is the input and output are completely isolated, so you don't have to worry about getting zapped by the output. You could also possibly connect two in series for a higher output voltage. Since the input goes through a bridge rectifier, you don't have to worry about polarity either. Most of them have very good regulation and overcurrent protection.

Each particular model may behave differently at low input voltage, so some testing would be needed to identify the minumum voltage the thing will actuall work on.

[TylerDurden]

Sweet.

UDM.

[knightmb]

That is cool, I'm glad that you found these and tested it to top it off

[Fush]

hey fletcher

Will this work on the plug pack switch-mode's or just the open case ones?
obviously it won't work on all switchmodes but if they do work on at least some of the plugpack ones that would be awesome.

this looks like it will solve a lot of my problems in regards to powering my lighting system.

Andrew

[fechter]

The case style doesn't matter. It does need to be a switcher, though. Behaviour at lower than specified input voltage will vary depending on model, so just try it and see what happens.

[recumbent]

Kewl Man I didn,t even know they were called switching power supplies Ha
I have two (10W&15W) high quality 1995 model 6volt headlamps that have a dead NICAD pack. Thanks for that.

[dirty_d]

couldn't you just make a simple buck converter with a 555 timer?

[Fush]

Hmmm...maybe..but at 72v its gets a bit iffy...

And plus its a lot simpler to run one of these swithmodes...just gut a transformer...hook up your power to the input wires...hook up your outputs and it works.

My setup is almost complete...i haven't tested it on 72v dc to see if it works...i might try that on Saturday when i am at work lots of SLA batteries in my shop.

Hope over to my thread if you want to see pics

Andews Ebike Build

[fechter]

It gets very tricky to make a good buck regulator for 72v with a 555. The idea is to avoid anything that resembles work. Most of us have these things lying around.

A good clue to look for on the switcher is a very wide input voltage range. The ones that go from 100v to 240v are more likely to work.

[fechter]

OK, I tested another small switching power supply. It's rated for 1.5 amp, 12v output.

I was able to run a 12v, 20w halogen bulb with the input all the way down to 30vdc! It would run a reduced load all the way down to about 24v input.
I don't think the maximum input voltage of 240v would ever be a limitation on any of my projects.

Forget about dc-dc converters!

[Fush]

OK, I tested another small switching power supply. It's rated for 1.5 amp, 12v output.

I was able to run a 12v, 20w halogen bulb with the input all the way down to 30vdc! It would run a reduced load all the way down to about 24v input.
I don't think the maximum input voltage of 240v would ever be a limitation on any of my projects.

Forget about dc-dc converters!

awesome mate...i just need to find a SMPS that will do about 1.5amp, my lights and my nokia charger blew my 1amp fuse last night so it means i need to get a bigger power supply...where about did you get yours?

[TylerDurden]

I was able to run a 12v, 20w halogen bulb with the input all the way down to 30vdc! [/size] It would run a reduced load all the way down to about 24v input.
Forget about dc-dc converters!

Outstanding.

Mass-quantities of LEDs should be a breeze.

[fechter]

awesome mate...i just need to find a SMPS that will do about 1.5amp, my lights and my nokia charger blew my 1amp fuse last night so it means i need to get a bigger power supply...where about did you get yours?

Hmm.... it came with a signal generator. I've seen similar models on some of the surplus places. There must be somewhere down there where you can find one. These are common with many computer printers and LCD displays.

Hint: look for ones that have an input range that goes from 100v to 240v.

[Fush]

hehe...well since we run 240VAC here it shouldn't be to much of an issue. I have found a few 4amp ones but i am trying to find something compact that i can fit in my box. I am pissed that it blew my fuse, but i might do some testing when i get my batts to find out how long it can handle more then 1amp.

[Malcolm]

Forget about dc-dc converters

Great stuff Fechter!

[Sound of footsteps disappearing towards attic, where old treasure is kept]

[Smoker]

Pure awesomeness. I would of never thought of it. I tried an ac adapter with 12v 1.5a / 5v 1.5a output connected to my 72v sla output and got the specified outputs. Thanks a bunch!

[Fush]

Hi all

Here is a video I created while at work today
<embed src="http://www.youtube.com/v/S-uB9f-Rg0Y" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"></embed>

The SMPS is the same as what I am using in my bike, except I striped the case away.

and yes i know I said hub motor I meant to say hobby motor...I didn't realised that I said that till I got home this evening and watched it...I also just notice that I said 56v, I really wasn't thinking that well when I made this...12x5=60VDC

Edit: ok fixed now

[vanilla ice]

I'm never thinking well so no worries there. I'm sure I have one or two of these things kicking around in the garage. Great idea.

[fechter]

Great vid, Fush.

You should try reducing the input voltage one battery at a time to see how low it can go before it loses output.

Small switching mode power supplies used to be quite rare a few years ago, but they seem to be on everything now, which is good for us.

I found several in my garage from old cell phones. 5v would be good for a LED light.

[Fush]

Great vid, Fush.

You should try reducing the input voltage one battery at a time to see how low it can go before it loses output.

Small switching mode power supplies used to be quite rare a few years ago, but they seem to be on everything now, which is good for us.

I found several in my garage from old cell phones. 5v would be good for a LED light.

We managed to get it working down to 48 volts but at that voltage the motor wouldn't start...if we started the motor at 60volts and then quickly change over to 48v the motor would continue running but again it wasn't as effective as 60v.

[fechter]

Good to know, thanks.

[fechter]

Here's one I got from http://www.allelectronics.com/

Part: http://www.allelectronics.com/make-a-store/item/PS-1233/12VDC-3.33A-SWITCHING-POWER-SUPPLY/-/1.html

Hipro # HP-O2040D43
Input: 100-240Vac
Output: 12Vdc 3.33Amp
Table-top style switching power supply. 5 ft output cord with ferrite bead for EMI suppression. Terminated with 2.5mm coax power plug, center positive. Includes three-prong IEC detachable power cord. UL, CE.
CAT# PS-1233

Your Price: $15.75 each


I got one of these, and this one fires up at 20v! Pretty close to full output at 24v. Over 24v, no problem.

[methods]

The topic I wanted to post on is closed: Cheap DC-DC converters for over 60v input.
viewtopic.php?f=16&t=2264

I spent a bunch of time making a post so I have got to put it somewhere. . .


TEST: Toshiba Notebook brick

MODEL: ADP-60RH A (V85)
SIZE: 4.5” x 1.5” x 1”

INPUT: 100 – 240V AC
OUTPUT: 15V 4A DC

*note: Most car alternators keep your battery voltage at somewhere around 14.4V or 14.8V so whenever selecting a “12V power supply” always try to shoot for a 15V unit. That will allow you to make more power for less current (smaller package).

**note: Bricks do not need to say “switching power supply” and in fact most don’t. Simply look for units that don’t look like they have a big heavy transformer inside. Nearly any laptop power supply will meet this criteria.

TEST DC INPUT: 100V, 50V, 36V
TEST LOAD: 4ohm 1% resistor (5.3ohms “hot”)


TEST 1) 100V input

No load input voltage: 100V
No load input current: 4ma
No load output voltage: 15.32V
No load output current: 0A

Loaded input voltage: 100V
Loaded input current: 642ma
Loaded output voltage: 14.5V
Loaded output current: 3.533A

Reality check:
Calculated load: 14.5/0.642 = 4.104 ohms (cold)
Actual load: 4ohms

No load input power: 100V * 4ma = 400mw
Loaded input power: 100V * 642ma = 64W


TEST 2) 50V

No load input voltage: 50V
No load input current: 4.5ma

Loaded input voltage: 50V
Loaded input current: 1.423A
Loaded output voltage: 14.5V

No load input power: 50V * 4.5ma = 225mw
Loaded input power: 50V * 1.423A = 71.15W

**note: Output current was not monitored
**note: Load was heating up so resistance ranged from 4ohms to 6ohms


TEST 3) 36V

No load input voltage: 36V
No load input current: 7ma

Loaded input voltage: 36V
Loaded input current: 1.57A
Loaded output voltage: 12.5V

No load input power: 36V * 4.5ma = 162mw
Loaded input power: 36V * 1.57A = 56.52W

**note: Output current was not monitored
**note: Load was heating up so resistance ranged from 4ohms to 6ohms


I have several others. The one I plan to use is 15V @ 5A
These are nice, clean, tight little packages. No soldering, water resistant, pre wired, slam dunk.

Thanks
Thanks
Thanks
Thanks
Thanks to Fechter for bringing this to our attention.

I just bought a Kelly that needs 12V – 24V and this will be the hot ticket. I am going to rig up a cig lighter too so that I can charge my cell phone etc. Maybe even a 110V converter so I can blow-dry my hair or charge my electric tooth brush.

-methods