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Parts explanation for A-stable multivibrator (TR type)


This is a transistor for the small signal amplification. The other transistor with the hFE=about 100 and the maximum collector current=100mA can be used. However, in case of the circuit this time, the 2SC type or the 2SD type must be used. 2SC or the 2SD type is NPN type and the electric current flows through the emitter from the collector. As for the difference of 2SC and 2SD, 2SC is for the high frequency and 2SD is for the low frequency. At the circuit this time, it cares about neither. There is 2SA or 2SB in the transistor. This transistor is PNP type. The direction of the electric current is opposite. So, it isn't possible to use for a circuit this time.It is possible to use if changing a circuit.


This capacitor is used to decide a repeat period. I used a cheap electrolysis aluminum capacitor. The capacitor of the other type can be used. This circuit is not a high frequency circuit. Therefore, the capacitor is to be OK if considering capacity and voltage. The voltage is the upper limit value with the voltage which is applied to the capacitor. Because the operating voltage of the circuit this time is 5V, more than 5V voltage isn't applied to the capacitor. There is no problem if using more than 10V one. As for the lead wire of electrolytic capacitor, positive and negative are decided. Pay attention so as not to make a mistake.

Light Emitting Diode (LED)

Light emitting diode (LED) has various shapes. The type of your taste can be selected. Depending on the LED, there are one where a blink feature is had and one where more than one device is included in one LED and so on. At the circuit this time, there is not a blink feature and the diode of the single device is used. When the LED lights up, the voltage of the LED both edges is about 2V. The attention point when using an LED is an electric current. Generally, it makes light up in the 10-mA electric current. Because the voltage of the LED is 2V, the voltage which is applied to the resistor is 3V(5V-2V). So R=3V/0.01A=300 ohm. This value doesn't have to be strict.


A 1/8-W type is used for the resistor. More than 1/8-W resistor can be used. The size of the resistor is larger. This time, I used a 1/8-W resistor to make compactly.


Studs are used as the leg of the printed board. The spacer of plastic can be used. It is to be OK if the wiring side of the printed board doesn't touch the metal which was put below and so on.

Wiring terminal

This is the terminal to connect a power. The power can be connected with direct to the printed board without using this terminal, too.

Printed board

The universal printed board to have cut in the size which it is necessary to do is used.