Well, the boxes were sold out, unfortunately 🙁
But i think we have a router(?) somewhere at home. Maybe i get some piece of solid oak to match my desk better and make my own box. Can't be too difficult. And it can be something funny to do during the winter.
And i think i will go with the Cmoy, it will be enough for me and it's god damn cheap to buy a kit from ebay.
Just a little question, how many hours can i listen with two 9v batteries?
But i think we have a router(?) somewhere at home. Maybe i get some piece of solid oak to match my desk better and make my own box. Can't be too difficult. And it can be something funny to do during the winter.
And i think i will go with the Cmoy, it will be enough for me and it's god damn cheap to buy a kit from ebay.
Just a little question, how many hours can i listen with two 9v batteries?
Look for specification on the mH hour rating of the particular brand and type of battery you're going to use. If you use a 4560 the idle current is usually a little less than 5 mA. You can do the math. Alternatively, you will find out how long it runs soon enough.
Just a suggestion, if you use that Ebay circuit/project posted earlier, don't put a 1k ohm resistor in series with the diode. It makes no sense when you can about triple the idle running time with no LED. Let's face it, 9 volts are Small batteries. Blue LEDs are fairly efficient. You can still use it to know the unit is on with only a few mA running through it, even in direct sun if you look into the diode. If you aren't apenuts for blue LEDs like it was 1995, you could use a red one that is painfully bright under 1 mA drive. I'd suggest starting with 4.7k and go down from there if it's not bright enough for you.
Personally, if I had a reason to use the 9-volts, I'd leave the light off.
Just a suggestion, if you use that Ebay circuit/project posted earlier, don't put a 1k ohm resistor in series with the diode. It makes no sense when you can about triple the idle running time with no LED. Let's face it, 9 volts are Small batteries. Blue LEDs are fairly efficient. You can still use it to know the unit is on with only a few mA running through it, even in direct sun if you look into the diode. If you aren't apenuts for blue LEDs like it was 1995, you could use a red one that is painfully bright under 1 mA drive. I'd suggest starting with 4.7k and go down from there if it's not bright enough for you.
Personally, if I had a reason to use the 9-volts, I'd leave the light off.
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Well, i'd actually prefer a little diode light to show if it's on or off. I can buy some higher quality rechargable batteries if needed.
But thanks for the input. But you only gave med the idle current, what's the load current?
But thanks for the input. But you only gave med the idle current, what's the load current?
Hi Rullknufs,
Yes the advantage of a pilot light is obvious, but it probably isn't necessary to have it beaming bright like shown in the Ebay picture. I looked at some Energizer 9 volt alkaline spec sheets. They don't go into very interesting detail like terminal impedance curves, but they give enough information to show that you should get 50 hours with about 5mA rms average output current (plus idle loss with no light). Quite low level, 1mW power with 40 ohm phones. At earsplittingloudandbooming level you might only get 3 or 4. If you want your ears when you get older, you'll get much more than 3 or 4 hours. Higher impedance headphones are better for running 9 volt batteries. 150, 300, and 600 are available.
Yes the advantage of a pilot light is obvious, but it probably isn't necessary to have it beaming bright like shown in the Ebay picture. I looked at some Energizer 9 volt alkaline spec sheets. They don't go into very interesting detail like terminal impedance curves, but they give enough information to show that you should get 50 hours with about 5mA rms average output current (plus idle loss with no light). Quite low level, 1mW power with 40 ohm phones. At earsplittingloudandbooming level you might only get 3 or 4. If you want your ears when you get older, you'll get much more than 3 or 4 hours. Higher impedance headphones are better for running 9 volt batteries. 150, 300, and 600 are available.
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Here's the sheet for an Energizer battery. Notice how you're rewarded for drawing less current. The battery seems to "get bigger" at lower currents in large part because of the cell resistance. As you draw less current that "internal resistor" doesn't burn as much power and more of it is available at the terminals. Actually, it's as if you're adding more resistance in parallel internall too as load increases.
http://data.energizer.com/PDFs/EN22.pdf
http://data.energizer.com/PDFs/EN22.pdf
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So, like 5 hours with a pair of batteries? That sounds terrible. I might even listen 5 hours straight on my headphones sometimes.
What would i need to do if i want to just plug it in with an oridnary powercord?
I am planning do my own box that is custom for the cmoy amp, so i could modify it to fit the power supply aswell.
What would i need to do if i want to just plug it in with an oridnary powercord?
I am planning do my own box that is custom for the cmoy amp, so i could modify it to fit the power supply aswell.
Adding a line supply is not too difficult, but you will probably want to get a transformer with a center tap and do the rectifier and filter yourself as has been suggested earlier in the thread. Running on a pair of 9 volts at least once through could be very informative for yourself though. Without any test equipment you could figure out what kind of average power you use. It won't mean much for the line supply design, since that will easily be "oversized" anyway, but it's good information nontheless, especially if you eventually want to resize the battery for portable applications.
I didn't really understand much of that. But what would a power-unit cost me and would it be difficult to build? And how big would it be?
There's a decent chance that by the time you're all done with this you will understand at least most of it. 25 bucks?, no not difficult at all. A transformer, 4 diodes or a bridge, and maybe 4 capacitors and a line cord and box will get you rolling. 10 cubic inches, +-.
Anyone on here can help you with the supply. Searching the boards will probably turn up a lot of circuits that are way more complex than you need at this point, but you might want to have a look.
Maybe no use overloading yourself right off. Battery supplies, even flimsy ones, have advantages that are very difficult to beat with anything that plugs in. Try building it up the way it sits, because it's easy, and go from there.
Anyone on here can help you with the supply. Searching the boards will probably turn up a lot of circuits that are way more complex than you need at this point, but you might want to have a look.
Maybe no use overloading yourself right off. Battery supplies, even flimsy ones, have advantages that are very difficult to beat with anything that plugs in. Try building it up the way it sits, because it's easy, and go from there.
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"
Power consumption
The CMoy's quiescent power draw, with or without its input plug connected, is 16 milliamps at nine volts.
Listening to something suitably doofy with my Sennheisers pumping about as loud as I'd ever want them to boosted the current consumption to a big 18mA or so. Taking the 'phones well and truly off and winding everything to eleven gave an average draw of a bit more than 20mA, with absolute screaming peaks up around 24mA."
Read the review here: Review: Chu Moy headphone amplifier
How long a would a 9v battery last? Or two?
Edit: He also mentioned like six AA Alkaline batteries would last more than 100 hours. That sounds pretty fair to me. What do you say, is it true?
Power consumption
The CMoy's quiescent power draw, with or without its input plug connected, is 16 milliamps at nine volts.
Listening to something suitably doofy with my Sennheisers pumping about as loud as I'd ever want them to boosted the current consumption to a big 18mA or so. Taking the 'phones well and truly off and winding everything to eleven gave an average draw of a bit more than 20mA, with absolute screaming peaks up around 24mA."
Read the review here: Review: Chu Moy headphone amplifier
How long a would a 9v battery last? Or two?
Edit: He also mentioned like six AA Alkaline batteries would last more than 100 hours. That sounds pretty fair to me. What do you say, is it true?
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