Automotive

Parts:
R1,R3____________1K 1/4W Resistors
R2,R5___________10K 1/4W Resistors
R4_____________220R 1/4W Resistor
R6_____________220K 1/4W Resistor
R7______________22K 1/4W Resistor
R8_____________100K 1/4W Resistor
C1,C2___________22µF 25V Electrolytic Capacitors
C3______________10nF 63V Polyester or Ceramic Capacitor
C4______________47µF 25V Electrolytic Capacitor
Q1,Q2_________BC557 45V 100mA PNP Transistors
Q3____________BC337 45V 800mA NPN Transistor
SW1___________SPST Toggle or Slide Main Switch (See Notes)
P1____________SPST Pushbutton [...]

Here is circuit power supply switching 12V. For Car PSU use IC UC3843 and mosfet IRFZ44N.
It is nice circuit for electronics PC MP3 Player. System control by digital circuit IC 74LS02
The next version will be much like the V2, except for a few changes:
* Added a trimmer (R13) to the R8/R9 voltage divider so it’s [...]

The circuit measures the car water temperature. CA3161 , CA3162 is a counter and 7segment driver to display amount of temperature on 7segments. The temperature sensor is a diode, 1N4148. This is set near of the Car Radiator. To obtain the 5V power supply from Car Battery, you can use a LM7805, +5V low cost [...]