19 12V to 24V DC-DC Converter using 555 IC

This DC-DC converter  steps up 12V from battery to 24V DC. The converter can deliver around 2A current or can power 40W to 50W of load. Click diagram below to enlarge.
DC-DC converter schematic

The heart of the circuit is the 555 timer IC that delivers pulses to the transistor. The frequency of the output pulses is around 653Hz and operated at 55% duty cycle. The transistor Q3 and zener D2 regulates output to 24V dc. LED  is for output voltage indicator. D4, R6, D3 and C4 regulate and filter the supply for the driver IC.

Part List:
R1 - 2.7 kilo ohms 1/4W
R2 - 10 kilo ohms 1/4W
R3 - 1.2 kilo ohms 1/4W
R4 - 120 ohms 1/4W
R5 - 1.5 kilo-ohms 1/4W
R6 - 47 ohms 1/2W
LED - red or any low power LED
C1 - 220nF
C2 - 100nF
C3 - 1000uF ( higher the better) electrolytic capacitor rated 16V
L1 - min 40 turns (60t is best) #20AWG in ferrite antenna bar
D1 - 6A rated diode or higher
D2 - 1N4749A, 1N5359B or 24V zener diode (min 1W)
D3 - 1N4739A
D4 - 1N4001, 1N4002, or similar
Q1 - TIP41C or NPN transistor with min 10W power capacity
Q2 - 2N3055 or similar NPN power transistor
Q3 - TIP41C or 2N3055
555 timer IC

Part list diagrams/pinouts: click to enlarge
TIP41 or TIP31 pins
555 IC pins
2N3055 pins
Ferrite winding in antenna rod (60 turns is better)


  1. brinkka2011 says: Just right points?I would be aware that as anyone who in reality doesnt write on blogs a lot (in fact, this can be my first submit), I dont assume the time period lurker is very turning into to a non-posting reader. Its no longer your fault in the least , however possibly the blogosphere may come up with a better, non-creepy title for the 90% folks that experience studying the content material .

  2. To friend brinkka2011
    What I understand in your comment is why would i use such a "creepy title" and not a very simple one?
    Well i make it that way so if ever they understand the title, I assume they don’t have any problem in building the circuit. My point is I don’t want and I don’t recommend my readers build something that they don’t understand, or build something that can harm them.
    The 12v to 24V converter above when built or fabricated wrong, there is a possibility that the output voltage is very high (1000V plus is possible) or current drawn is very large. Building it with very little knowledge can cause to damage to properties, and the worst thing is it can harm you.
    Keeping the title and some of the words too technical so only readers with enough background and experience can build the circuit. Making the title too simple invites inexperience reader to build it.
    Thank you for your comment and valuable inputs. Next time we will make some of the project easier so everyone can understand. Lots of thank to you.

  3. can you not replace Q1 & Q2 with a MOSFET?

  4. You can remove the two transistor and replace it with Mosfet. Mosfet is the best choice actually especially you need much higher power capacity.

  5. IRLB8743? with a heat-sink perhaps?

  6. Yeah, provide heatsink on transistors and diodes especially Q2,Q3, D2 and D1

  7. What dimension ferrite antenna bar do you use?

  8. does D1 needed to be a zener or a schottky?
    i had simulated this in a simulation software called multisim and it doesn't woked...what should i do? anyone here who made the circuit and made it worked?

  9. C3 is in the partslist as a 1000uf 16V. This will blow up if you put 24V on it. This cap needs to be at least 40V and low-ESR for good switching operation.

    For builders: also be aware that there is no current limiting on the output side. This can cause damage if a short-circuit occurs on the output.

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