{"id":224,"date":"2012-03-29T10:58:47","date_gmt":"2012-03-29T10:58:47","guid":{"rendered":"http:\/\/stompville.co.uk\/?p=224"},"modified":"2020-10-11T15:30:32","modified_gmt":"2020-10-11T15:30:32","slug":"altoids-piezo-pre-amp","status":"publish","type":"post","link":"https:\/\/stompville.co.uk\/?p=224","title":{"rendered":"Altoids piezo pre-amp"},"content":{"rendered":"

Update: Fully built and tested Altoids Piezo Preamps are available for sale in the shop here<\/a>.<\/p>\n

\"Altoids<\/p>\n

I’ve been taking my Altoids piezo DI box<\/a> to open mic nights and have had some interest and feedback.\u00a0 People seem to like the concept but are less impressed with the balanced output and phantom power – which is fair enough given that the mixer is invariably on the stage and the cables are relatively short.\u00a0 Consequently I have produced a simpler version of the unit and (as a result of ditching the op-amp)\u00a0 reduced the power consumption to about 0.3mA and increased battery life to 300+ hours.<\/p>\n

Here’s the schematic:<\/p>\n

\"Altoids<\/p>\n

So (compared with the Altoids Piezo DI) the balanced output has gone and there’s a TC54<\/a> low-battery monitor circuit which switches on the LED when the battery voltage falls to 7.3V.\u00a0 The battery is connected when a plug is inserted in the input socket.<\/p>\n

“Standard” PCB 1\/4″ jack sockets are readily available from many suppliers.\u00a0 However, the height above the board is a little high for an Altoids box so I have allowed for low-profile jack sockets.\u00a0 There are two versions of the PCB design.<\/p>\n