The CMOS Orchestra > 2017 > June
The OP-HPF High Pass Filter
I wanted to have an Isolator-style high pass filter device to play with. I found this design at https://www.eeweb.com/blog/circuit_projects/20hz-to-200hz-variable-high-pass-filter that uses a very common op-amp, the TL072. And there I found the design for a 555-driven negative voltage generator, needed for the TL072: https://www.allaboutcircuits.com/projects/build-your-own-negative-voltage-generator/ The only case I got is that Walkers biscuits box. Well English. I punched two holes to mount a rotary…
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