Design a Schmitt trigger using a IC 393 comparator (open-collector output) with thresholds at +1.0 volt and +1.5 volts. Use a 1.0 k pullup resistor to +5 volts, and assume that the 393 is powered from 15 volt supplies.

I think they are asking us to make the following circuit


simulate this circuit – Schematic created using CircuitLab

I have made the circuit but still not understanding how to setup R1,R2,R3,V2 to set the threshold voltage I think V1 will be out input.

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  • \$\begingroup\$ What have you tried? There are two states fully defined so you will have two equations, there are three unknows so you need to pick something else, more or less arbitrarily, like a reasonable resistance for one of the resistors. \$\endgroup\$ May 26 at 18:51
  • \$\begingroup\$ V3 provides wrong polarity (+ to GND). \$\endgroup\$
    – Jens
    May 26 at 18:56
  • \$\begingroup\$ @SpehroPefhany lets assume R1 to be 1k ohm so could please tell me how to find others \$\endgroup\$ May 26 at 19:20
  • \$\begingroup\$ @Jens thank you i will correct that \$\endgroup\$ May 26 at 19:21
  • \$\begingroup\$ Let's see your equations for the voltage at the non-inverting terminal. \$\endgroup\$ May 26 at 19:38


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