This motor speed controller uses a TDA1151 monolithic integrated circuit , designed by ST Microelectronics . TDA1151 motor speed controller circuit is designed in a SOT-32 plastic package and can be used for small applications where the space inside is very critical .
Also this circuit diagram can be used as speed regulator for DC motors of record players, tape and cassette recorders, movie cameras, toys or other low cost applications.
This speed controller circuit can provide a high output current up to 800 mA without any additional components and has a low quiescent current of 1.7mA .
The TDA1151 require a low reference voltage ( around 1.2 volts ) and it has a excellent parameters stability versus temperature .
The maximum voltage that can be applied to the TDA1151 is around 20 volts .
As you can see in the circuit diagram the TDA1151 require just few common external components and is very easy to design .
A very simple touch switch circuit diagram can be constructed using this circuit schematic . This circuit will turn on /off an electronic relay using the same touch sensor . This touch switch circuit is composed from an current amplifier and a decimal counter circuit . the counter circuit is a CDB490 type and is capable to show at pin 12 states 1 and 0 that depends by the pulse applied of pin number 14 . Pulses applied to pin 14 are provided by the current amplifier formed by that two BC transistors .
The circuit is require a 5volts power supply and can be used to turn on /off any other electronic circuit .
A very simple electronic touch switch circuit can be constructed using this schematic diagram . This electronic touch switch circuit is based on two transistors an can activate a relay , when the touch sensor is pressed .
The touch sensor can be constructed using a small piece of a printed circuit board ( two small tracks with a 2 mm distance between each other ) . This circuit is powered using a 12 volts DC power supply , so the relay used for this project must be a 12 volts relay . This circuit is working very simple , when both plates of the sensor are touched the skin resistance will activate the circuit .