Little Amplifier

I found this little amplifier (left, on two green boards) after looking for circuits to separate the treble from the bass, so as to power the woofer separately from the mid-range and tweeters. I found the circuit design, but decided it was wiser to buy an inexpensive amplifier that both separated bass from treble and amplified. All it needed was a transformer.The populated amplifier board cost about $10 on eBay. The transformer cost about $15. This was a few years ago. The amplifier is so small that I packed it with my electronics parts and shipped it to Taos. (The speakers were considerably larger and heavier.)

I have been plugging my iPhone into a radio at night and listening to classical music. But this little radio has almost no bass. So, bored the day after Thanksgiving, and not wanting to shop, I dug out the amplifier, speakers, and transformer, and hooked them all together for the first time. When I plugged the transformer into power I was prepared for a ‘pop’ and smoke, but all I got was silence. So I borrowed the audio cord from the radio and plugged my iPhone into the amplifier. Lo and behold, music from the speakers.

The balance was a bit heavy on the bass end, so I loaded the tuning app on my iPhone and went up and down the octaves, adjusting the treble and bass controls until the loudness seems to balance.

Having the transformer out in the open (with 120 Volts on connections) is not pleasing to either my eye or my sense of safety or visual beauty. Not having a power switch is a bit awkward, and not having a fuse might cost me the whole lot, so I ordered a box, power switch, and fuse (with holder). When that arrives I can enclose the whole thing and make it look more nearly professional. Getting all that mounted inside the box will occupy me for another day or so.

Checked the electricity use of the amplifier: 0.9 Watt with volume turned down. Max 7 Watt turned up loud. Very efficient.

Altogether I’m pleased with my efforts so far. And I have nice music to boot!

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