This prototype used an integrated amp IC, volume control, power switch, power light, etc. The power supply was a surplus wall transformer, rated 15VDC @ 1000mA. This unit is still in use today by an old friend in NY. This project was a good example of what could be built using some spare parts found in my myriad of parts cabinets and drawers.
Unfortunately, I don’t remember the exact amplifier IC that was used in this amplifier, but I do remember it was a (14-pin?) DIP chip that Radio Shack used to sell. Up to this point I had been using the LM386 for mono applications, however in this application I needed stereo, as well as more power. The IC used in this amplifier was a 2W / channel stereo amplifier IC that required very little in the way of support components and could also use a single supply rather than a dual-polarity supply. The enclosure, power light, slide switch, stereo potentiometer, RCA jacks and speaker terminals were all Radio Shack parts that I had on hand from various sales and mystery box purchases. The 15 VDC power supply was likely saved from an old answering machine or other device. The following photo shows what may be the IC I used.
The LM1877N-9 is a monolithic dual power amplifier designed to deliver 2W / channel continuous into 8Ω loads. The LM1877N-9 is designed to operate with a low number of external components, and still provide flexibility for use in stereo
phonographs, tape recorders and AM-FM stereo receivers, etc. Each power amplifier is biased from a common internal regulator to provide high power supply rejection, and output Q point centering. The LM1877N-9 is internally compensated for all gains greater than 10, and is a pin-for-pin replacement for the LM377 in audio applications.
- Wide supply range, 6— 24V
- Very low cross-over distortion
- Low audio band noise
- Internal current limiting, short circuit protection
- Internal thermal shutdown
- 2W / channel
- — 65 dB ripple rejection, output referred
- — 65 dB channel separation, output referred
- Multi-channel audio systems
- Stereo phonographs
- Tape recorders and players
- AM— FM radio receivers
- Servo amplifiers
- Intercom systems
- Automotive products
ABSOLUTE MAXIMUM RATINGS:
- Supply Voltage 26V
- Input Voltage ±0.7 V
- Operating Temperature 0°C to +70°C
- Storage Temperature -65°C to +150°C
- Junction Temperature 150°C
THIS IS A RESTORED ARCHIVE PROJECT AND AS SUCH MAY BE MISSING PHOTOS, PARTS LIST, SCHEMATIC, SOURCE CODE, ETC.