How to Build the CMoy Pocket Headphone Amplifier for $20
Okay, so you were intrigued by my claim that you can build a CMoy
pocket amp for US$20, but then disappointed when you saw that the parts
can easily crest $40. What’s the deal? It’s pretty simple:
in the main part of this article, I’m in a position to recommend
parts, which means I have to like the parts and I have to think
you’ll like them, too. That leads me to be conservative.
However, if you really wanted to skimp, here’s how you could
get the cost down to around $20:
| Description |
Qty |
ID |
Price |
Where to Get It, Comments |
| 220 µF/25 V electrolytic capacitor, radial leads |
2 |
C1 |
$1.00 |
Any electronics store will have these |
| 0.1 µF metallized polypropylene caps |
2 |
C2 |
$0.68 |
Digi-Key E1104-ND |
| Metal film resistors |
11 |
R* |
$1.21 |
Anywhere. 1/4 W metal film resistors average 11
cents each. |
| LED |
1 |
LED |
$0.10 |
Any electronics store will have these |
| OPA2134PA |
1 |
IC1 |
$2.63 |
Digi-Key |
| Chunk of protoboard |
1 |
BOARD |
$1.50 |
Radio Shack |
| 1/8" jacks |
2 |
IN/OUT |
$2.00 |
Digi-Key, Mouser, or Newark. More expensive at
Radio Shack. |
| Power and level switches |
2 |
SW |
$5.00 |
Radio Shack, Mouser. The NKK ones at Digi-Key are nice, but
expensive. |
| Basic enclosure (PacTec HML) |
1 |
BOX |
$6.00 |
Radio Shack, Newark, Mouser. |
| Total: |
$20.12 |
In the above part list, I include the same enclosure Chu Moy
used for his original amp. It’s not actually a very popular
enclosure, however; personally, I find it rather ugly. Mint tins are
more popular, partly because they save you several bucks, and many
think they look good.
Counterbalancing this are many things that can inflate the cost:
Taxes and shipping
Basic supplies like wire, shrink tubing, and electrical
tape.
When mail ordering, there are various incentives to
order more than just the exact parts you need for a single
project. You might want additional resistors for gain or
LED brightness tweaking. You might
want a few different op-amp types to “roll,” so
you can find the ones you prefer. Your parts distributor of
choice might have certain order minimums you must observe.
The parts set above configures the amp for its original
conception, with a level switch instead of the more popular
later version with a volume control (potentiometer) and its
associated knob.
The parts list doesn’t include sockets, but I consider
it a must for a first time DIYer, and strongly advised in any
case.
Back to the
article...
|