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I am trying to control the movement of a remote controlled car by using a 8051 microcontroller. In the remote controller circuit there are four push buttons(forward, backward, left, right). I need to replace these 4 push buttons with 4 switches that can be controlled by digital logic signal coming from my MCU. However, the input voltages to these switches are sinusodial waves whose frequencies are 40 MHz and amplitudes vary in 0-3V range. What should I use? I have thought of something like a tri state buffer but they work with digital inputs as far as I know. I think a MOSFET could do the job but I don't exacty know how it works. Any ideas?

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    \$\begingroup\$ Your description seems rather unlikely. Most likely the switches have either DC across them or are polled at a rate of maybe 1kHz- so you would see square (rectangular) waveforms. Make sure you have the ground connection on your oscilloscope probe connected to the circuit ground. \$\endgroup\$ Commented Nov 26, 2017 at 20:43
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    \$\begingroup\$ With only four buttons the chances are good that they simply connect a controller input pin to ground or battery negative. Inspection of the PCB or testing for continuity between the button pins and ground should answer this. \$\endgroup\$
    – Transistor
    Commented Nov 26, 2017 at 21:06
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    \$\begingroup\$ SN74HC4066D works from 2~6V for Vcc \$\endgroup\$
    – D.A.S.
    Commented Nov 26, 2017 at 21:24
  • \$\begingroup\$ Can you recommend me a thread to follow since I don't have a comprehensive knowledge on transistors, or any other easier and more suitable ways to perform this task? \$\endgroup\$ Commented Nov 26, 2017 at 21:28
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    \$\begingroup\$ since you are replacing mechanical switches, using mechanical relays is one of the options. \$\endgroup\$
    – jsotola
    Commented Nov 26, 2017 at 21:34

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