You can see some of the pictures here:
MAX756 DC-DC Step UP
I’ve built this for one of the LED projects I’m working on. Very good refresher on reading schematics and applying them to the real world. The power supply will provide 3.3V or 5V out with a minimum of 0.7V in. (Requires 1.1V to start.)
More info on the IC here:
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1167
[Update: 2006/05/15]
Made the MAKE Blog today.
18 Comments
am interested in this device but cant find the max756 in the uk is there an equivalent part
regards
robert
I got mine as a sample from Maxim. I have seen them available at places like Digi-Key, I would expect there are a few suppliers already in the UK.
I’ve not yet seen an equivelent for Maxim chips. I guess that the patent isn’t run out yet or it’s just not economical to copy them yet. There are some alternative ways to build a step up switcher using other ICs, but they usually take more components.
I found (via http://www.hackaday.com/) a pdf on how to create a dc-dc step-up to replace a 9V battery here:
http://www.bairesrobotics.com.ar/elektor/10-2003%20SuperCap%20Battery.pdf
I’ve mirrored the pdf here:
http://anton.lr2.com/media/SuperCapBattery.pdf
Could you please tell us what LED(s) that you used in this build?
I used a single super bright 10mm LED in the mini mag light. I don’t remember the brand, but I bought them from one of the vendors on eBay. They were shipped direct from Hong Kong.
I’d recommend using a 5mm LED. A 10mm hole removes a little too much material from the reflector and it cracked after a couple months of use. With the LED the reflector doesn’t do much if anything, but it is necessary to work the switch when rotating the lens.
Hey Anton,
The article that I wrote about your LED project got promoted to the front page of digg.com. It has generated tons of hits, and I am sure a lot of them went to your site. I hope this has not increased your upload too much, and caused you a lot of money. If so, I am sorry, but hopefully it did drive you some hits. I really liked your project though.
Greg Lipscomb
DIY Live
Do you have a list of part numbers that you used ?
Hey I am a compleate hardware building noob. I have never built a circuit before but I am super interested in this project. Do you have a step by step tutorial on how someone like me can build this?
Jared,
I don’t have a step by step howto, but if you’re a complete noob I’d recommend starting out with something a little cheaper. There are quite a few electronics DIY projects on the web. I’ll dig up some links later tonight and post an article with them.
Some of these components are sensitive to heat and/or static so they might not be the best beginner project. Some practice learning to solder is a good start. You can also check out RadioShack (just don’t ask for help, they’re clueless). They used to have a small book of projects for the 555 timer that wouldn’t be a bad starting point.
I’ve linked to a good timely getting started article on DIY Live here:
DIY Live – Electronics Tutorial
Right on Anton. I mean I am computer Savy and I can Solder just fine. I used to be an Auto Mechanic and did a lot of electrical work. I just don’t understand how to lay out compnents ina sequence to achieve a certain effect. Any tips on how to learn what order to place components in to obtain an effect I am looking for? how about good places to buy excellent components?
Ah nevermind I see you have posted up some great links about how to do all this stuff.
Frequently now it’s just a matter of finding a chip that does most of what you need and looking at the reference circuit in the chip’s documentation.
Most of the components around a chip are used to make inputs conform to the limits. In the case of the dc-dc step up the coil, diode, and capacitors provide some oscilation to drive the switcher.
Converting the schematic to a physical layout is up for interpretation. Unless you’re dealing with high frequencies or current it’s not usually that critical where the components go. I chose the layout I did here because of the parts that I had on hand and the constraints of an AA sized space.
Here are a couple good links for some info on how DC-DC power supplies work.
http://www.powerdesigners.com/InfoWeb/design_center/articles/DC-DC/converter.shtm
http://en.wikipedia.org/wiki/DC_to_DC_converter
i chopped up a rope light to grab the leds out if it….talk about cheap:)
I was wondering if you could configure me a converter to convert roughly around .7 to .9V to 3 or 5V… unfortunately the source is a small fuel cell and I really can’t tell you how much it produces… but if I put a 19.2 ohm motor on the cell the voltage reading reads .76
Zane,
This type of step-up isn’t well suited for driving a motor.
The circuit doesn’t produce more power, it just alters it a bit, and in fact loses some in the conversion. The Max756 has a maximum output current of just .3A.
If you could find a 5V motor that’d run as expected at that amperage, you’d have to supply about 1.8 amps at 1V to drive the circuit and the motor.
5V * .3A = 1.5 Watts = 1V * 1.5A
Add in the losses of the step-up (guess 80%, won’t be any better than 90) and you’re over 1.8 amps.
In reality the motor will probably draw close to .5A or more, especially when load increases.
Hi! I have a question. If I attach a 3 volt power supply to Vin, will this circuit output volts? Thank you!
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