This General Electric circuit is from the 80's. The PUTs used in this meter are not common components today.
January 2017 - Texas Instruments' new TLVx376 series precision operational amplifiers can now be...
We found this circuit in a 90's Radio Electronics. The low power circuit activates a 12 V relay...
This simple stage can operate with low frequency signals (audio), driving a small lodspeaker....