{"id":4343,"date":"2020-09-14T15:18:14","date_gmt":"2020-09-14T15:18:14","guid":{"rendered":"https:\/\/www.richardmudhar.com\/blog\/?p=4343"},"modified":"2020-09-14T22:55:45","modified_gmt":"2020-09-14T22:55:45","slug":"tinkering-with-piezo-contact-mics-on-low-voltage-power-supplies","status":"publish","type":"post","link":"https:\/\/www.richardmudhar.com\/blog\/2020\/09\/tinkering-with-piezo-contact-mics-on-low-voltage-power-supplies\/","title":{"rendered":"Piezo contact mics on low voltage power supplies"},"content":{"rendered":"

A few years ago I did a couple of piezo contact mic amplifier designs<\/a>, because people often moan that these things sound tinny and crap. There’s a wrong way and a right way to use these – they want to work into a high impedance. Using Piezo Contact Mics Right<\/a> sets you right. Trouble is these use a 9V battery, and it seems world + dog want to use 5V, because that’s what they had. Time was when power supplies were +\/- 15V for analogue and 5V for digital, but that’s a different story for later.<\/p>\n

So what can you do with your piezo contact mic at 5V then?<\/h3>\n

Not much. If you are looking for low signal level performance an emitter follower biased at an output of 2V would work well, but if you only have 5V available it’s likely you are trying to digitise this signal and bung it in an Arduino or something. In that case, think laterally. Toss the power supply. I developed those amps because as a field recordist I wanted to hear faint signals from the contact mic. You know, like the whispering in the rails as a distant train approaches, though you need to avoid the Fredzania Thompson ending.<\/p>\n

These days people would look at you funny if you attach a box with wires to the underneath of the rails. Don’t try this at home and all that.<\/p>\n