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Recommendation for single-box MidiDAC PSU?
MUFF WIGGLER Forum Index -> Oakley Sound Systems  
Author Recommendation for single-box MidiDAC PSU?
drip.feed
If I wanted to house just a MidiDAC in its own little enclosure (to give me a portable MIDI-CV unit) could someone recommend a decent power supply for it?

EDIT:
Would something like this be good enough?
http://www.ebay.co.uk/itm/15-Volt-DC-Power-Supply-15v-Regulated-PSU-Ma x-1A-/290668442931?pt=UK_Computing_PowerSupplies_EH&hash=item43ad30753 3#ht_1833wt_1397
Synthbuilder
drip.feed wrote:
If I wanted to house just a MidiDAC in its own little enclosure (to give me a portable MIDI-CV unit) could someone recommend a decent power supply for it?


Difficult to do properly as you'd need a split rail regulated output wallwart or linelump. And as far as I know one doesn't exist in the UK. The one in the Ebay link is single rail (just one +15V not +/-15V) and probably a noisy switch mode thing.

There's nothing wrong with switch mode supplies but the ones in the wall warts tend to be pretty shabby. They generate way too much stray fields and have a noisy or squealing output.

Personally if you are looking for a standalone midi-CV then you'd be better off buying a Kenton box. Ready made, housed in a nice little box and comes with a guarantee. You'd be hard pressed to build one cheaper:

http://www.kentonuk.com/products/items/m-cv/prosolo.shtml

Tony
drip.feed
Synthbuilder wrote:
Personally if you are looking for a standalone midi-CV then you'd be better off buying a Kenton box. Ready made, housed in a nice little box and comes with a guarantee. You'd be hard pressed to build one cheaper:

http://www.kentonuk.com/products/items/m-cv/prosolo.shtml


Thanks Tony. I looked at the Kenton already but it only has 1 AUX output which makes it very shit compared to your MidiDAC which has 6 AUX outputs. I want velocity, aftertouch, mod wheel, bender and CC. Even Kenton's Modular-Solo product has only 4 AUX's and is resolutely Euro rack. I would have to go to the Kenton PRO 2000 MkII to get 6 AUX's and that is expensive (though very cool). It's hard to find a MIDI-CV box out there that has as many outputs as the MidiDAC.

EDIT:
Actually, I have been unfair about the little Kenton Pro Solo. It has a ton of internally configurable options that make the AUX output more flexible than it first appears. It can also output 0 and +5V on each of two pins of the MIDI THRU port which might be useful.
krisp14u
You could try this Not cheap but would power much more than just a MidiDAC
http://uk.farnell.com/xp-power/pcm50ud08/psu-low-leakage-50w-2-output/ dp/1109902?Ntt=1109902

I totally understand the desire for the MidiDAC I have 2 and could use more

The MidiDAC slide is very nice Rockin' Banana!
drip.feed
krisp14u wrote:
You could try this Not cheap but would power much more than just a MidiDAC
http://uk.farnell.com/xp-power/pcm50ud08/psu-low-leakage-50w-2-output/ dp/1109902?Ntt=1109902

Good lord. That is overkill, isn't it? Would the Yamaha PA-20 work just as well?

You can tell I don't understand power supplies, can't you?

Tangent:
You know what would be a cool hack for the MidiDAC? Retrofit one of these: http://www.alyseum.com/product_ALeX.php
Synthbuilder
drip.feed wrote:
Would the Yamaha PA-20 work just as well?


Nope. The Yamaha PA-20 is an centre tapped AC output device and as such needs to be rectified (turned into DC) and then regulated to exactly +15V and -15V.

Since you only need a small amount of current you can get away with a single phase AC wallwart like the Maplin N57AT. The output of this will need to be rectified, smoothed and regulated. Ken Stone of CGS sells a little power supply board that does this and gives the output on a standard four pin MOTM/Oakley header.

http://www.cgs.synth.net/modules/cgs14_psu.html

You probably wouldn't need any heatsinks just to drive one midiDAC. Just connect the AC power from the Maplin wallwart onto one of the 18VAC inputs and 0V on Ken's board. Maybe put a switch in series with the inlet socket so you can put the midiDAC into standby.

Tony
drip.feed
Synthbuilder wrote:
Since you only need a small amount of current you can get away with a single phase AC wallwart like the Maplin N57AT. The output of this will need to be rectified, smoothed and regulated. Ken Stone of CGS sells a little power supply board that does this and gives the output on a standard four pin MOTM/Oakley header.

http://www.cgs.synth.net/modules/cgs14_psu.html

You probably wouldn't need any heatsinks just to drive one midiDAC. Just connect the AC power from the Maplin wallwart onto one of the 18VAC inputs and 0V on Ken's board. Maybe put a switch in series with the inlet socket so you can put the midiDAC into standby.

Tony


Thanks again Tony. Ken has discontinued that little board and has replaced it with the CGS66 Linear Power Supply which looks a lot like your own power supply merged with a Dizzy. Could the Oakley PSU be driven from that Maplin wallwart?
magman
I picked up one of these PSU's from Quarndon for one of my projects:

http://quarndon.co.uk/index.php?main_page=product_info&cPath=56_79&pro ducts_id=17974

This is a small linear PSU with about 200mA per rail. It suspect it should ideally be mounted on a PCB for the safety though, with a proper mains connection (switched and fused).

There are similar PSU's at Farnell (with a PCB as well), but these are more than double the price:

http://uk.farnell.com/lascar/psu203/psu-pcb-2-output/dp/1183258

Hope this helps.

Regards

Magman
drip.feed
magman wrote:
http://quarndon.co.uk/index.php?main_page=product_info&cPath=56_79&pro ducts_id=17974

This is a small linear PSU with about 200mA per rail. It suspect it should ideally be mounted on a PCB for the safety though, with a proper mains connection (switched and fused).


Thanks Magman, that might fit the bill perfectly. But I don't understand what you meant by 'mounting it on a PCB for safety'.
Synthbuilder
drip.feed wrote:
Could the Oakley PSU be driven from that Maplin wallwart?

Yes. Full instructions to do this are given in the User Manual. It's probably well worth reading the UM completely but the sections on pages 9 & 10 in the UM deals with the Maplin adapter.

http://www.oakleysound.com/psu.htm

I reckon you wouldn't need any heatsinking at all for one midiDAC. Simply build the PSU module and solder the power devices sticking up vertically in the air.

Tony
Synthbuilder
drip.feed wrote:
Thanks Magman, that might fit the bill perfectly. But I don't understand what you meant by 'mounting it on a PCB for safety'.


I'll just jump in here. Mike means that that power supply is designed to be mounted on a circuit board. This circuit board would have copper traces on the underside that would connect to the power supply's pins. Those copper traces would be out of harms way since the board would be mounted in such a way as you could never touch them. The traces would then connect to well insulated power terminals also mounted on the board. Those terminals would then be connected, via appropriate wiring, to the mains inlet, fuse and switch. The latter devices could also be board mounted negating the need for the terminal and any hand wiring.

If you haven't dealt with mains power before I'd leave this one alone. It's not difficult but if you do make a mistake it can kill you or someone else. I always recommend wallwarts or line lumps since they keep the high voltages away from you.

Remember if you make contact with the UK's 240V supply it will, at best, really hurt and, at worse, will kill you.

Tony
drip.feed
Thanks again Tony. It all seems so obvious when you explain it. oops

I was thinking it might be cool to DIY the MidiDAC in that 1U 19" version then mount it in one of these:



Build cost (very, very ball park)

Oakley PSU Kit: £19
CNC Panel: £40
Mouser parts: £70
Knobs, pots, jacks, etc: £30
Maplin wall wart: £13
Metal box: £26
Shipping: £25
TOTAL: £223
ashleym
How about one from here?

[url=http://www.quasarelectronics.com/cfe073-symmetrical-power-supply- module-15vdc-500ma-+-230vac-transformer.htm]quasar electronics[/url]
Synthbuilder
Thanks for that Ashley. Beats me why that link is not working. This seems to work though:

http://www.quasarelectronics.co.uk/cfe073-symmetrical-power-supply-mod ule-15vdc-500ma-+-230vac-transformer.htm

Of course, you do have to do the mains wiring on this one. Again it's nothing too difficult but cock it up and there'll be trouble...

Tony
ashleym
I 100% agree that if you are in any way unsure of mains and wiring it dont get a kit. No money saved if worth the potential danger. If you arent sure get the "sealed" unit recommended by Krisp1. ambulance
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