MOS tube single button electronic switch

This is a single-button self-locking electronic switch circuit simulated using Circuit Wizard. If you know the fixed operating voltage, the circuit will be simpler. If you are not sure, you need to refine the value of the feedback circuit so that Q2 is at critical operation. status, thereby achieving self-locking working status.

Note (the circuit only passes the simulation test, please verify it yourself):
1. Support voltage: 3-12V, the maximum support is 15V during simulation, please design and verify higher voltages by yourself;
2. When the working voltage is 3-5V, only You need to keep Q1-Q2, R1-R6, C1, and SW. 3. For
5-9V working voltage, you need to use Q4, R7, R8.
4. When 9-12V, you need to use Q5, R9, and R10.
5. The best in the circuit Incorporate a D1 pressure relief diode to prevent the capacitance incorporated in the subsequent circuit from interfering with
6, Q4, and Q5. The main purpose is to reduce the sampling voltage value and make Q2 at the critical value. Therefore, if it is a certain operating voltage, it can Fix the resistor value
7 in series with R3. Q3 is mainly to speed up the voltage release speed of C1 and reduce the waiting interval for shutdown after startup. C2 is mainly to increase stability.
 
Analysis of working principle:
1. After power-on, the base of Q2 is extremely low, causing cut-off , so Q1 G is at a high level and is cut off;
2. When the SW switch is pressed, C1 is fully charged, and C1 discharges to Q2, causing Q2 to be turned on, Q1 G is turned into a low level, and R3 is turned on. The feedback circuit formed can continuously supply power to the base of Q2 to achieve self-locking conduction;
3. After releasing SW, C1 discharges through R2 and becomes low level;
4. Press SW again, and the charging process of C1 will Q2's base voltage is pulled low and turned off, Q1 is turned off due to the increase in Q2's cutoff G electrode voltage, and the R3 feedback circuit also loses voltage, so Q2 lacks the conditions for continuous conduction and self-locks off;

Disclaimer: This circuit has only passed the simulation and has not been actually tested. If you are interested, you can try it. After all, the circuit is very simple under a certain working voltage. See the figure below for details: