I am planning to upgrade a simple timing circuit that puts out an ultrasonic
tone burst when triggered. Currently the circuit uses 2 '555 timers. One is
the tone and one is the gate. I would like to replace this portion with a
12Cxxx part. Does anyone have experience with the internal osc?
- Will it be as accurate as my RC(5% tolerance) timing over temperature
(-20F to 130F)?

- -Mark