This circuit of starting lights for auto-race was found in an English documentation from the 80's. The LEDs must be of different colors, for greater realism.
This small transmitter with 2 transistors can reach several hundred meters using a 30 to 70 cm...
This circuit was obtained in a 1977 Radio Handbook. The transistor is from the era and the coils...
This charger can be used with one to four AA, AAA, C or D cells. The maximum current is given by R...