Sorry I’ve been so quiet recently, been busy building some things.
First up is a CMOY headphone amplifier in a mint tin. Plans are here and here and it really can be made for around $10-$15 is you have some resistors, sockets and stripboard lying around, $25 otherwise.
This one has a fixed 10:1 amplification using the cheaper OPA2134P op-amp chip, which works perfectly with my cellphone’s volume control for feeding into the car stereo. It’s simple enough to add a volume control if you need one. The internal wiring is the best I could do without having any shrink tubing to hand. The next one will be much prettier inside… (the eternal cry of the perfectionist)
An excellent second project, and converting the layout from protoboard to stripboard is good practice for rethinking component layouts.
No idea yet. Two 9V batteries running a low power amp and a single LED can’t take too much juice, guess I should try to measure it. My guess is a month or two of occasional use? Certainly better than the phone!
I bought one of Bioscience geeks CMoy amps (the original maker of them) and I have to say that that hooked up to my iphone with my V-Moda Roox earphones makes every piece of music an experience. I would highly recommend one!
Second attempt is a little smaller, a little neater and uses a TLE2426 “rail splitter” for a better balanced power supply that will help the batteries last longer. Additional cost: an extra $1.24. I’m mad with money, me.
Having said that, the previous batteries are still at 7.5v after a month of daily drive time and occasional workplace use.
Well, that last one didn’t work for reasons unknown. So I set about redesigning the amp from scratch and found out that fighting the stripboard is a dumb idea. Go with the flow, stick your virtual ground as a central line and things get a lot easier.
I think I need to put one of these in my Zero 4, the headphone output is pitifully weak. Well at least compared to the firebox…I swear that thing could blow technics of your head at full
Cool project- but just buy a Ray Samuels Shadow instead.. Or if you like tube sound… go for the Millet Hybrid tube amp at ttvj.com I own two and LOVE THEM.
