DC converter 6V to 12V by BD679
This circuit is power supply circuit, again the circuit that have the merit is if we want dc voltage 12V but , we have 6 volt only the circuit can modify DC voltage 6 Volt be 12VDC get.
The principle works of the circuit is Q1, Q2, R1, R2, R3, R4, R5, D1, C1 and C2 build the circuit is model astable multi vibrator give output be Square Wave. Which be positive pulse signal at have many frequency. And have R6 perform be limit current already flow come to reach at a pin B of Q3 and a pin C of Q4 in this condition current at flow come in pin way B of Q3 make Q3 bias. But Q4 still not bias. Because of still have no current bias at a pin B. When Q3 bias make have current flow through L1, D2 change ZD1 cause drop voltage at ZD1.
Which be output voltage and voltage this increase continually poverty voltage that equal to 12 the volt. By have R7 be limit current already change come in the way pin B of Q4 make Q4 work be make Q3 stop bias. Then make output voltage be 0 volt, but when positive pulse signal that made come to then change come to at R6 then make Q3 bias again. And work character as before but there are many speeds then can make output that appear can come out 12 volt all the time by have C3 perform in something current filter smoothly before increasingly lead output voltage go to be usable.
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Categories: DC converter Tags: 6V to 12V, step up dc converters, transistor dc converter
6v to 12v converter by TDA2003
This 6V to 12V converter circuit is made with an IC from SGS with several additional components. The IC is a TDA2003 but it can be replaced with a TDA2002. The cost of building the 6volts to 12 volts converter should be low enough to justify constructing it instead of modifying the entire equipment setup to work directly with a 6 volts power supply. The two principles of simplicity and functions properly without the need of the transformer.
The IC1 opam functions as a stable power multivibrator. Its oscillation frequency is determined by C3. Its oscillates at around 4kHz at standby and increases in a loaded condition up to around 7kHz. The output of the IC2 opamp is identical to the IC1 oscillator signal but in the opposite phase.
When the output of IC1 is at zero, the C4 charges via the diode D1 up to the power supply level minus the voltage drop at D1. When the IC1 swings to the opposite direction, its output become positive. The output voltage from IC1 adds up to the voltage stored at C4 forcing the diode D1 to stop conducting. C5 then charges via the diode D2 to a voltage that is double than the power supply level.
The theoritical output could reach the triple of the supply voltage. TO guard against unnecessary voltage increases at low current consumptions, a limiter stage was added to the circuit composed of a 15 volt zener diode and a darlington transistor T1/T2. This stage caps the output voltage to about 14.2 volts. To fiter out ripple from the output, C8 was also added. This helps prevent the hum signal from being noticed on radio or audio devices.
In constructing the 6 to 12 volts converter, attach the ICs to a common heatsink close to the pcb. THe transistor must be attached to a separate heatsink. To get a much higher current output from the converter, C4, C5 and C6 must be increased to 2200uF.
Source: http://apowersupply.com/6v-to-12v-converter-tda2003-144.html
Categories: DC converter Tags: 6V to 12V, step up voltage converter, TDA2003







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