DC-to-DC Converter

I built this DC-to-DC converter for my 48V electric bike because I wanted to be able to plug-in some common 12V accessories, e.g. my cell-phone charger, or a GPS unit.

Step 1 Schematic

Here's the schematic. The cap values are somewhat flexible depending on how much ripple you can tolerate. Be sure to observe the correct polarity for the electrolytic caps. I do not have a list of Digikey part numbers because I found many of the parts I needed at a local electronics surplus store. But all these parts (or something close) are available from Digikey.

Comments

[cam1128]

How would you make a 90V to 50V converter (with low amp levels)?

[frank_w12]

is there a way to go from 15 to 12

[scd]

That's probably easiest to accomplish with a simple linear regulator such as a  7812 .. I found a 7812 datasheet here:

http://www.datasheetarchive.com/7812-datasheet.html

[fatboyslim]

Is there a way of having in input of between 9-15 volts and achieving a ouput of 48-60volts?

[scd]

Yes, but not with this circuit.  What you are looking for is called a boost converter.

[kentdream]

LM2576HVT - 12 should do the job, however 2576HVT-12 only provide 3A output.

thz author SCD. I was also searching for a 48dc to 12dc for my electric bike.

maybe we can share more ideas about e-bike =)

[silencekilla]

can you give us a list of the electronics components please?

[scd]

Since I found many of the parts I needed locally, I don't have Digikey part numbers for everything, but I have updated the Instructable with a parts list including Digikey part numbers or substitutes where possible.

[kelseymh]

Very nice idea! To make it easier to reproduce by others (not everyone is familiar with building circuits or wiring connectors), could you consider showing some additional steps or details?

• Provide a list of the necessary components, and sources (e.g., RS part numbers) if possible.
• How are the Molex (? hard to tell from the pix) connectors pinned out?
• What does the back of the perf board look like?
• Use image notes to call out each component (on both sides of the board)
• How did you make the car-lighter dongle?
• It looks like you had to drill a clearance hole in the case for one of the caps.
• You're using nylon standoffs because the case won't close?

[scd]

The car-lighter dongle came from my local auto-parts store. The connectors are one-off types from my local electronics surplus store but almost any 2-pin connector would work. Yes I had to drill a clearance hole for the larger cap. Yes, the nylon standoffs were needed because the case wouldn't close but I see that as a feature because it allows for airflow to the regulator :-) I will try to improve the Instructable with more info. Thanks, Scott

[NachoMahma]

. kelseymh makes some excellent points on how to make your iBle better, but, if one assumes that the reader has just a little bit of experience, it gives all the info needed. As is, I'd rate it 2½-3; with his suggestions incorporated and a few more details on assembly (eg, how the components are connected), possibly a 4. More info on theory of operation and how to adapt for other uses will give it a slight boost. . If the unit will be used for anything close to the rated 3A, a heatsink would be a good idea. Probably not an issue for cell phones and GPSs (?½A max?).

[BobS]

Not visible, no components list. This way it cannot be built. How about formulas to calculate different in and outputs; or make it variable/ adjustable? How about current?

[scd]

This particular switcher is not adjustable. It is 12V only. There are other similar switching regulators that do provide adjustability. The components are listed on the schematic and the output current capability is 3A (listed as a note in step 3)

[atombomb1945]

Agreed, I would love to find out how to build this and step it down for a 24v system (Military Vehicles)

[scd]

This would work as-is with a 24V input voltage.

[mykelpogi]

can you pls give more specific details on materials like voltage on capacitor , what kind of diode is shottky,inductor.. plss plss. can i use LM2575 instead of LM27576 more details pls.. because i real like to try ur work many thanks