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Overlay and PDC 10 ?

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Hello everybody,

My overlay is working fine when is connected with the Garmin GPS12, but if I connect the PDC 10 in parallel, the GPS data are instable, at least the data that I can see on the monitor, and the PDC 10 isn’t working.

How I can connect both the equipment to the GPS?

Any ideas?

Thank you,


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Your gps is probably not transmitting as strong an RS232 signal as many typical RS232 devices do. The RS232 transmission voltages are probably in the -5 to 5 volt range (I forget, but it is much lower than normal RS232) instead of -10 to +10 volts as a computer or MAX232 will transmit. If you have another gps try it, or if you are good at building you may be able to find a chip similar to the MAX232 that will relay the signals to the higher standard levels. The PDC10 uses a receiver that is comparable to a MAX232, which should work in parallel circuits, assuming that you have a typical transmitter. Do you know what the receiver circuit in the overlay device is?

Best Regards,


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