I am trying to design an inductance and capacitance meter with multiple scales, to achieve this I thought a multiplexer can do the job, but it didn't.

My question is: What is wrong in this design and how can I select between the capacitors without a multiplexer?

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L1 is the inductor plug. The meter should measure the tank circuit resonance period using a comparator.

  • 2
    \$\begingroup\$ What you need is called an analog switch, not a multiplexer. \$\endgroup\$ – Hearth Mar 17 '19 at 17:19
  • \$\begingroup\$ @Hearth that would still be unlikely to work due to parasitics. \$\endgroup\$ – Edgar Brown Mar 17 '19 at 17:36
  • 2
    \$\begingroup\$ @EdgarBrown It'll work a hell of a lot better than a multiplexer! But yes, it's not the best choice. \$\endgroup\$ – Hearth Mar 17 '19 at 17:37
  • \$\begingroup\$ Is relay a good choice? \$\endgroup\$ – Gustavo Ale Mar 17 '19 at 17:42
  • 1
    \$\begingroup\$ I don't think you have any real chance of using that 1pF capacitor, C2. The parasitics will be many times bigger. \$\endgroup\$ – Elliot Alderson Mar 17 '19 at 17:51

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