Hands Free Mobile Kit
One of our club members, Ralph VK3LL published an article in the early ’90s describing a hands fee mobile unit.
The need for hand free microphone operation, is even greater now with more of our members installing AR transceivers in their vehicles. Ralph VK3LL has come to the rescue with an updated design now featuring a PIC microcontroller with PCB, that has made the project simpler to build.
| Safety | Keep both hands on the steering wheel whilst operating your radio transceiver. |
| Improved TX audio | The electret microphone is at a constant distance from the user’s mouth and tailored for optimum frequency response within your particular vehicle |
| No more curly cord | A tiny (8mm x 15mm) microphone can be discreetly installed to provide a neat and tidy installation – XYL approved |
Features that have been designed into the Hands Free kit.
| Adjustable microphone gain control |
| Adjustable bass and treble audio equalisation |
| All adjustments are made using 25-turn trim-pots for fine ‘tweaking’ |
| 8 choices of on-board timeout duration (0.5min, 1min, 2min, 2.5min, 3min, 4,min, 5min, 10min) |
| Two RJ45 connectors – one to the radio’s mic socket and the other for microphone loop-through |
| Momentary pushbutton PTT switch used to provide greatest versatility |
| Flashing LED provides “on-air” indication |
| Visual indication 10 seconds before imminent timeout |
| Low cost of parts |
| Easy construction on a single, high quality PCB |
| All ‘thru-hole’ parts, no SMD soldering required |
| Uses a low cost electret microphone (supplied in the kit) |
| No adjustments or mods inside your radio are required |
| Designed to work with just about every radio transceiver, using jumper pins on a 16-pin header… |
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Kit construction video guide
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