I want to "step up" 3vdc (battery) to 4vdc. to drive an LED. Can I do this with a simple coil transformer? I want to keep the size under
7mm diameter.- posted
15 years ago
I want to "step up" 3vdc (battery) to 4vdc. to drive an LED. Can I do this with a simple coil transformer? I want to keep the size under
7mm diameter.
You don't need a transformer. Build a boost converter, or just use one "in a can" if uncomfortable doing that. All it needs in terms of magnetics is a regular inductor out of a catalog. If you want to be extra good use a shielded inductor. For LED use it might be best to use a converter that mainly regulates for current instead of a fixed output voltage.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Transformers don't work with DC.
As Joerg suggests, use a boost converter -- for just one LED you can probably get by with an off the shelf coil, particularly if you don't mind some inefficiencies. 7mm diameter shouldn't be a problem at all.
There should be approximately one bazzilion designs on the web if you look, some of which actually work for their intended purpose, and a few of which will work for you.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html
You can use an ICL7660 charge pump IC with a capacitor in a doubling circuit. A 555 timer may also work, but you might need the CMOS version for
3 VDC, and then the output current might not be sufficient.Paul
Plus another 2-3 bazillion in application notes from TI, National, ON Semi and so on :-)
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
A TinyLogic schmitt oscillator and a few more parts could build a nice little charge pump. 4 parts total, I think.
John
An old thread...
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Think things are bad now? Wait until Obama "takes care" of you.
As already mentioned, a transformer isn't what you need. However, you can wind an inductor that's part of a boost circuit that will light your LED. The circuits on this page aren't tightly spec'd (see the flooring nail layout) but they will give you something to experiment with.
-- Rich Webb Norfolk, VA
Nonsense. They work fine, under the right conditions.
Best regards, Spehro Pefhany
-- "it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
ftp://66.117.156.8/Led_Pump.JPG
John
Explain your "right conditions". Unless you have a magnetic monopole mine, you can't make a transformer couple energy with constant current.
They're inherently AC devices.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html
Nice defined operating frequency, huh ?:-)
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine Sometimes I even put it in the food
See, for example:
It was invented by a guy named Ivar Giaever (who shared the Nobel prize with Esaki of tunnel diode fame).
In most cases it's not a very practical solution for lighting LEDs, I must admit.
Best regards, Spehro Pefhany
-- "it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Not real bad, actually. Add a pcb pour cap if you want to pad it out.
I was tempted to remove yet another part, namely short the schmitt input and output. That might have been controversial, and we certainly don't want any controversy here.
Digikey wants 5.6 cents for the gate (by the reel), under 1 cent for the resistor, and maybe a couple of cents each for the cap and diode.
10, 11 cents total, maybe.John
That's cheating.
And while I could see a practical use for such a device for signal transmission in extremely stringent conditions, I doubt it'll ever make it as a power converter.
(It'd be interesting if it did, though).
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html
And it can blink, too! For certain values of R and C.
John
Make it an NAND or NOR gate (or a "universal" logic gate -- NC7SZ57 or '58) and you can have an enable line as well...
google 'joule thief' designed for 1.5V operation but can probably be made to work on 3V.
There must be some way to make a chaotic oscillator from a multi-input schmitt gate and a couple of RCs. Yet another rainy-day project.
John
Certainly something that everyone needs ;-)
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine Sometimes I even put it in the food
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.