A variable voltage "Zener" can be done using this electronic scheme. Compared to Zener diodes normal input impedance is higher (20 ... 50 ohms), lower peak load and temperature coefficient of only about -2 mV / ° C. However, the circuit is quite simple and use can be modified in the field of 3 ... 25 V. Once the voltage of T1 is greater than 0.6 V, the transistor leads, therefore, lead and voltage T2 can not grow, like a Zener diode. R2 sets the ratio between P1/R2 and Zener voltage of the circuit.
A 12 to 24 volt converter can be designed using few common electronic components. When the bottom FET drive first electrolytic capacitor is charging. After this, the upper FET drive, it goes down in blocking state. Negative terminal of the first electrolytic capacitor is now found at 12 V, positive terminal, in contrast, is at a higher voltage 12 V, ie at 24 V. This voltage reaches a diode to the output electrolytic capacitor, which stores output voltage during charging the first capacitor.
This voltage inverter circuit is designed using common electronic parts . This voltage inverter circuit, produces a negative voltage from a positive one. Control current of 1 mA flowing through the resistance R1 is taken by a rectangular oscillator signals. If there is a 0 logic input transistor T1 is blocked and the entire current flows through R2 into the base of T2, capacitor C1 is charged by the emitter current of T2 (C1 capacitor voltage increases to the power supply voltage).