For present-day owners of vintage Commodore computers, keeping data and programs safe and backed up is top priority. Disk drive storage was more common in the US, whereas in Europe, the audio cassette was the preferred medium of storage.
The Datasette device was what allowed interfacing the cassettes to the computer. Tape head alignment was critical to successfully writing and reading data to the cassette. Some models of the Datasette came with a small hole above the keys, to allow access to the adjustment screw of the tape head azimuth position. Tweaking this while looking at a signal meter could help you improve the signal from a bad cassette and prevent load errors. [Jani] tried a commercial solution called “Load-IT” which had a LED bargraph, but it couldn’t help much dealing with tapes with very bad signals. So he built a signal strength meter for his Datasette. He calls it the VU-sette since it uses an analog style meter quite similar to the VU-meters found in many audio equipment.
The hardware is simple and uses commonly available parts. The analog meter is extracted from a Battery Checker sourced from eBay. An op-amp drives the analog meter, and another transistor drives a separate speaker. This can be used to listen in on the cassette, if the speaker is enabled via a push button. [Jani] first breadboarded and tested the circuit before ordering out prototype boards.
To test performance, [Jani] used FinalTAP, a tool for examining, cleaning and restoring digitized data cassette tapes (TAP files) for the Commodore 64 computer. The “LOAD-IT” version worked well with tapes that were in fairly good condition. But his VU-sette version allowed him to adjust the head more precisely and get out a much better read from bad tapes. While on the subject, check out this nice 7-segment bubble LED digital counter for the 1530.