Originally Posted by JimN
What "make"? TrueRTA and RoomEQ Wizard are free programs that have signal generators and in the case of TrueRTA, you can choose sine, square, triangle and sawtooth wave forms. You just need to interface the output with the tach.
Hum, I don't know anything about these programs. It appears that the output amplitude is indicated in dB's.... which should be fine if you know what the equivalent voltage amplitude is. The tach/hr meter is looking for a minimum frequency with in a 5 to 12 volt amplitude. And you need some way to output that to the tach.
Quote from the Faria tech: "It is a sine wave. You need at least a 5 volt signal. When the tach pointer is over 500 rpm it starts counting. 50 - 100 Hz should work."
My 555 circuit is more of a sawtooth but it worked. S