While the customer who wanted this won't be able to see it (he's blind), this is a mod to the STD counter for clicking output. I adopted Joe Sousa's excellent idea for a "tick to tock" converter here, with a little more malice aforethought - out came the Beranek and I actually designed this more on pupose for a high Q (about 20) and a resonance around 1.5khz. I had a tiny earphone transducer from my Dad's old collection of things to try for tactile stimulators for deaf, that just fit. I cut a piece of 1/2" tubing about .9" long, and used a 3/16 hole through the box as the output "bass reflex" port, on the bottom.
Here's what it looks like topside.
Now, the signal after the voltage divider to take it from ~80v down to TTL levels for the counter input is still pretty high impedance, so a single transistor doesn't have enough beta to drive a 12 ohm speaker directly without loading the signal down too much. Rather than fool with the existing divider circuit, I just made up a darlington pair so as not to load this too much. I didn't use the customary E-B resistor on the second transistor, as I didn't want this to be fast! Since the signal is normally pulled up to 5v, I used pnp's as an emitter follower, with the load between the 5v rail and the emitter of the pair. I gooped this down with hot glue for ruggedness. Since this customer is blind, I also made up a stainless steel screen for the mica tube window so it'll be a little harder to poke it out with a finger or a sample. This is also put on with hot glue, the idea being that if something gets stuck in there, you can peel it back off pretty easily and safely to get it removed.
Here's the driver blob.
Since he's using a screen reader on his computer to get usable information out of it, I'm also adding a command pair to the STD counter software itself - after this, typing a 't' to it will put it in "output only every ten seconds" mode, and typing an 'o' to it will revert to outputs once per second. I can't even read the long lines by eye once a second...The power up state will be the normal one, nothing extra to do for anyone else - the software for the PC will work the same either way, but just get fewer data points in the "ten second" mode.