This dc to dc converter raise a dc voltage at almost a double value and is useful for raising the output voltage of solar batteries up to the required level for charging acid or NiCad batteries. It can deliver up to 3Amps. The measurement values with 2A load are shown in the bottom table.
In this dc converter article we assume that the input voltage is 12V and the output is 22V. IC1a, R2 and C5 build a square wave generator. This signal is available in reversed form at IC1d output. The R2-C6 network delays the IC1a output signal, so at the AND/OR gate of IC1b we find a filling factor > 0.5. The same thing is available for AND/NO IC1c output.
IC1c output is passed through 3 levels: in IC3f, IC3a and the four gates connected in parallel IC3b-IC3e. Then it is used to command t3 FET. IC1b commands T1 and when this transistor conducts, the common point of R6-R7 will drop at 2V in the absence of D1. T2 and T3 conducts alternatively. When T2 conducts, C10 charges untill the input signal level through T3 and D3. When T2 is blocked and T3 conducts, C9 is charging in the similar way. It is essential that D2, D3, T2 and T3 to have a good cooling. For the best, mount them on a common heatsink.
The bold lines represent high currents circuits which must be as short as can be, because it transport up to 6A. A very well constructed dc to dc converter can have as much as 94% efficiency (at 22.2V and 1.8Amps)