Nemo de Monet
100+ Head-Fier
- Joined
- Oct 15, 2008
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To be honest, I'm not sure why I'm even bothering posting this, since everyone here seems to have some sort of obscure and irrational objection to powering anything from computer USB power. That said, the idea gets raised fairly often, so...
I have designed and tested a USB power supply based around Texas Instruments' DCP0105 family of isolated power converters. It measures 37x26mm (somewhat smaller than a 9V battery), uses a minimal component count, is reasonably idiot-proof, and works very well.
It is designed to replace the 9V battery in a Mini^3 amplifier; the rearmost mounting hole lines up perfectly with the "ribbon" hole on the Mini^3 PCB, allowing the two to be joined with, e.g. a nylon 3-32 nut and bolt. This positioning leaves the B-type USB connector protruding approximately 3/16" from the rear panel of the Hammond enclosure, which I think is convenient; flush mounting is possible through use of something like double-sided tape.
(The prototype PCBs were made by BatchPCB, who I've confirmed by email somehow experienced a production error, which caused the groundplane to be omitted; hence the ugly wiring under the PCB. Production boards, if any, will use the headers at the "inner" edge of the board, as intended.)
It could, obviously, be used to power a number of other designs from USB power, as well, and can be used with non-USB power, too: There's a spot for a two-pin, 0.100" header under where the USB connector goes, allowing use with an alternate power source and any of the TI converter chips in the same DIP-14 package. (The TI chips, incidentally, are stackable in the same way BUF634s are, so you could, for example, stack three 2W converters on top of one another and get a 6W supply... though not, obviously, from USB power.)
It's also fully compatible with the DCP* split/dual-output chips.
I've built a prototype using the DCP010515, and tested it for several hours with my "extended-runtime" Mini^3; it performs flawlessly.
Fused for 250ma input, the board should be able to provide about 940mw of power; exact current depends on what chip, and thus voltage, you use; mine uses the 15V DCP010515, and should be capable of over 60ma output - several times more than the Mini^3 should ever need.
I'm willing to do a group buy of these boards, if anyone's interested. Since this is not a profit-making venture, I'd be just as happy to let someone, like Seeed Studios over in China (see link in my signature), fab and sell the boards instead. If I have 'em fabbed, they'll be gold-plated, and cost around $3 USD each, plus shipping; if someone else does 'em, they probably won't be gold-plated, and will still cost around $3 USD each.
Also, I have a pair of the prototype boards left over; if anyone in the U.S. wants to test one of these, I'll send you a board, free; just post here and I'll PM you. Board only; you'd have to provide everything else, which includes:
(for a single-voltage power supply)
1 x PCB-mount USB "B" connector (Digi-Key ED90064-ND or similar);
1 x Texas Instruments DCP0105nn or DCP0205nn power converter chip;
1 x resettable polyfuse, 1206 size, 5V or better, 100-250ma (Digi-Key F2110CT-ND or similar);
1 x 1uf capacitor, 1206 size (Digi-Key 587-1326-1-ND or similar);
1 x 2,2uf capacitor, 1206 size (Digi-Key 587-1329-1-ND or similar);
(optional) 1 or 2 3mm or 5mm LED (1 is one the USB side; the other is on the input side; there's little point to having them both populated.);
(optional) 1 or 2 0805 size current-limiting resistors for the LEDs;
(for a split-voltage supply you'd add another 1uf capacitor, and use a split-voltage chip.)
All the parts, from Digi-Key, will run you under $20 USD; that includes having to get 10ea of two capacitor and one resistor values. The non-SMD parts for additional boards would run you under $12 USD each.
For retro-fitting to a Mini^3, CMoy, or similar 9V-powered amp, the easiest connection method is probably to use a 9V battery snap with leads, wired "backwards". I intend to do this, but haven't, yet, because I wanted to be able to more easily measure voltage and current on the prototype.
My goal is not to (try to) compete with Joneeboi's integrated USB-powered Mini^3 design, which uses the same TI converter chip; rather the goal is to offer a modular design that can be retrofitted to existing Mini^3s, or used for a variety of other projects.
That's all I got: let the flaming, trolling, obsessive pessimism, unhelpful comments, and insincere expressions of interest begin.
I have designed and tested a USB power supply based around Texas Instruments' DCP0105 family of isolated power converters. It measures 37x26mm (somewhat smaller than a 9V battery), uses a minimal component count, is reasonably idiot-proof, and works very well.
It is designed to replace the 9V battery in a Mini^3 amplifier; the rearmost mounting hole lines up perfectly with the "ribbon" hole on the Mini^3 PCB, allowing the two to be joined with, e.g. a nylon 3-32 nut and bolt. This positioning leaves the B-type USB connector protruding approximately 3/16" from the rear panel of the Hammond enclosure, which I think is convenient; flush mounting is possible through use of something like double-sided tape.
(The prototype PCBs were made by BatchPCB, who I've confirmed by email somehow experienced a production error, which caused the groundplane to be omitted; hence the ugly wiring under the PCB. Production boards, if any, will use the headers at the "inner" edge of the board, as intended.)
It could, obviously, be used to power a number of other designs from USB power, as well, and can be used with non-USB power, too: There's a spot for a two-pin, 0.100" header under where the USB connector goes, allowing use with an alternate power source and any of the TI converter chips in the same DIP-14 package. (The TI chips, incidentally, are stackable in the same way BUF634s are, so you could, for example, stack three 2W converters on top of one another and get a 6W supply... though not, obviously, from USB power.)
It's also fully compatible with the DCP* split/dual-output chips.
I've built a prototype using the DCP010515, and tested it for several hours with my "extended-runtime" Mini^3; it performs flawlessly.
Fused for 250ma input, the board should be able to provide about 940mw of power; exact current depends on what chip, and thus voltage, you use; mine uses the 15V DCP010515, and should be capable of over 60ma output - several times more than the Mini^3 should ever need.
I'm willing to do a group buy of these boards, if anyone's interested. Since this is not a profit-making venture, I'd be just as happy to let someone, like Seeed Studios over in China (see link in my signature), fab and sell the boards instead. If I have 'em fabbed, they'll be gold-plated, and cost around $3 USD each, plus shipping; if someone else does 'em, they probably won't be gold-plated, and will still cost around $3 USD each.
Also, I have a pair of the prototype boards left over; if anyone in the U.S. wants to test one of these, I'll send you a board, free; just post here and I'll PM you. Board only; you'd have to provide everything else, which includes:
(for a single-voltage power supply)
1 x PCB-mount USB "B" connector (Digi-Key ED90064-ND or similar);
1 x Texas Instruments DCP0105nn or DCP0205nn power converter chip;
1 x resettable polyfuse, 1206 size, 5V or better, 100-250ma (Digi-Key F2110CT-ND or similar);
1 x 1uf capacitor, 1206 size (Digi-Key 587-1326-1-ND or similar);
1 x 2,2uf capacitor, 1206 size (Digi-Key 587-1329-1-ND or similar);
(optional) 1 or 2 3mm or 5mm LED (1 is one the USB side; the other is on the input side; there's little point to having them both populated.);
(optional) 1 or 2 0805 size current-limiting resistors for the LEDs;
(for a split-voltage supply you'd add another 1uf capacitor, and use a split-voltage chip.)
All the parts, from Digi-Key, will run you under $20 USD; that includes having to get 10ea of two capacitor and one resistor values. The non-SMD parts for additional boards would run you under $12 USD each.
For retro-fitting to a Mini^3, CMoy, or similar 9V-powered amp, the easiest connection method is probably to use a 9V battery snap with leads, wired "backwards". I intend to do this, but haven't, yet, because I wanted to be able to more easily measure voltage and current on the prototype.
My goal is not to (try to) compete with Joneeboi's integrated USB-powered Mini^3 design, which uses the same TI converter chip; rather the goal is to offer a modular design that can be retrofitted to existing Mini^3s, or used for a variety of other projects.
That's all I got: let the flaming, trolling, obsessive pessimism, unhelpful comments, and insincere expressions of interest begin.
