negative signal

[martho]

I have a hold graupner transmitter and I found the PPM signal on the circuit but It is negative and with 2 volts amplitude, will it be OK to make a interface

[Steve Lewin]

If you connect it via a capacitor to a circuit intended for JR (low amplitude) it should be o.k. It will not work with the very cheap zener diode/resistor circuits, it will need at least a transistor for amplification.

Steve

[Mike Roberts]

Hi

Go to my website and look at the circuit diagram for JR and try that. Go via R/C projects>FMS>IRQ Serial>Circuit for JR.

Cheers

Mike

[Steve Lewin]

Mike's circuit is a good one and it works with JR because they have a capacitor in the transmitter. For safety I'd still suggest connecting the signal in via a capacitor unless you're absolutely certain that it is capacitively coupled in the transmitter. 100nF should be o.k.

Steve