A quick one following on the heels of the 8-Track tape backup —
While it’s fun to kick a technology when it’s down, it’s not as satisfying as making something that actually, y’know, works well. And I had some 8-track parts left over, particularly the guts of another tape unit whose amplifier circuitry and read/write head were fried.
In the process of making the tape backup unit one of the well-known flaws of continuous-loop tape reared its head — you can’t rewind. This made testing painful, since testing 5 seconds worth of DTMF tones meant running through a complete cycle of the tape. Even on fast forward this can take some minutes.
So I built an 8-track rewinder. It seems like this is a cosmic punchline, like the DVD rewinder — of course you can’t rewind an 8-track. But you can fast-forward it to the beginning.
This one runs its motor until the foil strip somewhere on the tape loop temporarily completes a circuit. This circuit latches a relay which shuts off the motor; the relay stays on, and thus the motor off, until the tape is pulled:
Here’s the unit I started with:
I trimmed off the excess stuff:
…and mounted the circuit:
I hate dealing with wall warts and had a bit of extra space inside, so ended up hiding the power supply inside the chassis.
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