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Small Mosfet transistor to high power Mosfet driver

ceech Hardware Contributor last edited by ceech

This is quick tip on how to drive a power mosfet transistor with a small one. Let's say that we would like to drive a pump with a wireless signal and that we have one of those boards with a N channel mosfets on:

We need to make a few modifications:

Connect D3 and D4 with a bridge, change a D1 diode with a 1k resistor and connect:

Those changes make up to this schematics:

And here are the signals:

The blue signal is the output from the digital pin D3( PWM ), and the yellow signal is the signal on the gate of the power mosfet, which is a P channel mosfet.
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I have success! (oops, that's suppose to be Timer1) I only sample for 1/60 of a second. What I did was to back up all the timer registered I used and then resorted them after I was done sampling. (As opposed to initializing the registers in setup and then starting the timer when needed.) Now I have a Nano sampling the data and sending it to a MySensors Gateway on an RPi3B+ which then sends it to an MQTT broker runing on an old laptop. Also running on the laptop is Home Assistant running inside of VirtualBox. If MySensors does use Timer1, it appears that restoring the registers allows it to be shared. //------------------------------------------------------ISR ISR(TIMER1_OVF_vect){ // interrupt service routine for overflow TCNT1 = TimerPreloadValue; // must be first line! starts the timer counting again digitalWrite(TRIGGER_START_SAMPLE_PIN,HIGH); samplesVolts[--sample]=analogRead(VOLTS_IN_PIN); // decrement before capturing samplesCurrent[sample]=analogRead(CURRENT_IN_PIN); digitalWrite(TRIGGER_START_SAMPLE_PIN,LOW); if (!sample){ // count down to zero digitalWrite(TRIGGER_START_SAMPLE_PERIOD_PIN,LOW); // indicate that sampling is complete samplingEnd = micros(); TCCR1B &= 248; // turns off timer } } //------------------------------------------------------sampleOneCycle void sampleOneCycle(){ // back up timer registers uint8_t TCNT1_b = TCNT1; uint8_t TCCR1B_b = TCCR1B; uint8_t TCCR1A_b = TCCR1A; uint8_t TIMSK1_b = TIMSK1; // configure timer which starts the sampling noInterrupts(); // disable all interrupts TCCR1A = 0; TCCR1B = 0; TCNT1 = TimerPreloadValue; // preload timer //TCCR1B |= (1 << CS10)|(1 << CS12); // 1024 prescaler TCCR1B &= 248; // turns off timer? TIMSK1 |= (1 << TOIE1); // enable timer overflow interrupt ISR // demark sampling sample = NUMBER_OF_SAMPLES; // count down to zero digitalWrite(TRIGGER_START_SAMPLE_PERIOD_PIN,HIGH); samplingStart = micros(); TCNT1 = 65535; // first trigger right away! TCCR1B |= 1; // turns on timer interrupts(); // enable all interrupts // wait for sampling to be complete while(digitalRead(TRIGGER_START_SAMPLE_PERIOD_PIN)){}; samplingEnd = micros(); // restore timer registers TCNT1 = TCNT1_b; TCCR1B = TCCR1B_b; TCCR1A = TCCR1A_b; TIMSK1 = TIMSK1_b; }

Small Mosfet transistor to high power Mosfet driver

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