The Museum of HP Calculators

HP Forum Archive 09

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Using the speaker for output
Message #1 Posted by Andy on 10 Dec 2002, 11:32 a.m.

I recently purchased a beat-up 75D on ebay for $5.50. When I received it, I noticed a small hole drilled into the side of the 75 with two wires running out of it.

Upon putting in a new battery, the 75D worked (of course). After trying a few commands, I noticed there was no beep upon errors. So I tried the BEEP command and nothing happenend.

So, I hooked the two wires up to my mulitmeter and put the multimeter in Hz mode. I typed 440,5 BEEP on the 75 of sure enough, the multimeter displayed 440 for 5 seconds.

I know the 75d has hpil (but useless without HPILCMDS or the I/O rom (belive it or not, this $5.50 75 actually had an I/O rom in it ! :) ! )). So one could use the speaker output to turn a device on or off...or since it can output a variety of signals, one could have it turn many devices on or off.

Since many hpcalcs have speakers, this technique could be of use on them as well. Has this been done before? I know that the 41's time module has been utilized in a somewhat similar fashion.

Andy

      
Re: Using the speaker for output
Message #2 Posted by Andrés C. Rodríguez (Argentina) on 12 Dec 2002, 5:32 p.m.,
in response to message #1 by Andy

Please take a look at my article in the Memories Forum ( http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/memories.cgi?read=22 ), where I mentioned my experiences with the HP41 speaker for output.

Also see the photos at the end of the article.

Best regards


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