Daryl Musashi
New Member
I am building a count-down timer, which stops at "00". An astable 555 timer generates the pulses for the count-down and is stopped by another IC by switching PIN 4 (reset) from HI to LOW at this moment.
I want to use this signal from PIN 4 to activate a small 4.5 - 9 V DC motor for a certain time. The idea of this part of the circuit is: the LOW signal from PIN 4 is inverted, this HIGH signal switches a PNP transistor (common emitter). The collector of the transistor emits a negative voltage to trigger PIN 2 and activate the monostable 555 timer for a short moment. While the 555 timer is activated a HIGH signal is emitted by PIN 3. Between PIN 3 and GND the small motor is located.
When I test the circuit the motor is as planned activated when the count-down has reached "00"- but the motor does not stop after once activated. Where is my mistake?
Another question in this context: How can a delay between the signal of PIN 4 (astable 555 timer) and the activision of the motor can be realized?
I want to use this signal from PIN 4 to activate a small 4.5 - 9 V DC motor for a certain time. The idea of this part of the circuit is: the LOW signal from PIN 4 is inverted, this HIGH signal switches a PNP transistor (common emitter). The collector of the transistor emits a negative voltage to trigger PIN 2 and activate the monostable 555 timer for a short moment. While the 555 timer is activated a HIGH signal is emitted by PIN 3. Between PIN 3 and GND the small motor is located.
When I test the circuit the motor is as planned activated when the count-down has reached "00"- but the motor does not stop after once activated. Where is my mistake?
Another question in this context: How can a delay between the signal of PIN 4 (astable 555 timer) and the activision of the motor can be realized?