DC 2 DC problem - Page 1
Forum section: electronics / general

author: jarleiceman
author_rank: Contributor
timestamp: November 30, 2013, 06:38:43 pm
content: HelloI'm a man from the Cold North...Norway, and I have a question about DC2DC...:I shall use this in a set of active headphones..and there are a 1,5v AAA batery here, but the voltage is to low...I have to have at least 2v for it...(not more than 3,5v..)and the current is less than 100 mA, so I wonder if you have a solution for my project:with a small capasators diodes and resistor (at easy at is can be...) I dont want to use active compenents (like Op-Amps etc...)mabe a dobler of the voltage how do I do it....(I see I can use a DC.DC boost converter), but I want too make it cheap and with as less components as posible....senserlyjarleiceman

author: vk6zgo
author_rank: Super Contributor
timestamp: December 01, 2013, 12:33:51 am
content: Two AAA batteries in series gives you 3 volts.

author: Skimask
author_rank: Super Contributor
timestamp: December 01, 2013, 01:18:41 am
content: http://www.amazon.com/UltraFire-Rechargeable-Battery-CR10440-Lithium/dp/B0046R6TIU

author: IanB
author_rank: Super Contributor
timestamp: December 01, 2013, 01:28:54 am
content: Quote from: jarleiceman on November 30, 2013, 06:38:43 pmHmm...Quote from: vk6zgo on December 01, 2013, 12:33:51 am...oh yes! What an idea!Ask yourself, can you make a circuit with capacitors, diodes, resistors (and yes, transistors), that fits in a space smaller than an AAA battery? Will it also be cheaper than an AAA battery? Fewer components than one AAA battery? More efficient than one AAA battery?By Jove, I think I see the answer! The cheapest, simplest, most efficient voltage doubler is a second AAA battery! Two AAA batteries in series gives you exactly what you are looking for!

author: peter.mitchell
author_rank: Super Contributor
timestamp: December 01, 2013, 03:35:09 am
content: Quote from: IanB on December 01, 2013, 01:28:54 amA round of applause for this man!Quote from: jarleiceman on November 30, 2013, 06:38:43 pmHow do you know not more than 3.5 just curious? If allowed more than 3.5, eg, 4.2, you could use a lithium 10440 cell.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 01, 2013, 06:04:12 am
content: I kept reading & re-reading it to see if I'd missed something pertinent,but it seems just what it says---he wants to get around 3v with AAAs.Hence my suggestion of two in series!I've noticed a lot of people want to go for the most complex way of doing things,regardless of whether there is any advantage In doing so.

author: jarleiceman
author_rank: Contributor
timestamp: December 01, 2013, 02:25:58 pm
content: Of course I'v think about 2 AAA...and get 3v...but there isnt PLACE..... O0jarleiceman

author: mariush
author_rank: Super Contributor
timestamp: December 01, 2013, 03:38:21 pm
content: I already gave you a solution, with that LT1037 ... with the SOIC version and smd inductor, diode and capacitors, you can fit in half the space of an aaa battery and it will basically be a few mm tall.Here's the post:https://www.eevblog.com/forum/beginners/dc2dc-1-5v-to-2v/msg339940/#msg339940Here's my project : a 9v battery replacement ... The LT1037 takes 1v-2.7v from the supercapacitor and makes ~5.7v for a multimeter with 9v battery holder (the meter says battery low at 5.5v).You don't need the trimpot at the top, you can just use a fixed resistor to get your voltage, i wanted to be able to adjust it. You can also move to everything surface mount and basically get it to use much less space. I went with prototyping board and all through hole :

author: jarleiceman
author_rank: Contributor
timestamp: December 01, 2013, 05:23:59 pm
content: Yes Mariush, I'm goinig for the LT1037...thank you for the serios and good answer, just what I was loocking for

author: TheBorg
author_rank: Frequent Contributor
timestamp: December 01, 2013, 09:51:18 pm
content: Quote from: jarleiceman on December 01, 2013, 05:23:59 pmWhat type of headphones is it? I'm sure if they left place for a replaceable battery they would've made it easy enough to find an actual replacement.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 01, 2013, 10:59:28 pm
content: Quote from: jarleiceman on December 01, 2013, 05:23:59 pmWell,had we known you had two threads running,it might have helped.You also appeared to be have limited knowledge.I'm still very dubious-----the volume of an AAA is very small.& really small inductors are not very efficient.You gave the impression that you were quite restricted in what you could easily obtain,but if you can get the LT1037 & stuff like that,you could also useSkimask'ssuggestion with one or two series diodes to reduce the voltage to your requirement.

author: jarleiceman
author_rank: Contributor
timestamp: December 02, 2013, 04:39:55 pm
content: Thanks guysYou say: "You also appeared to be have limited knowledge"...I'not...my English isnt very good..but I have a very good eduqation in data- & Electronics, and then I have been a high school teacher on in Data- & elecronics for about 10 years, but then I had a strooke (brain) and i'm working hard too come back...but I know my way around electronic, but as I sayed it been some years seence I practice.....and yes the simplest soloution is Skimask's suggestion with one or two series diodes to reduce the voltage...And its BOSE Comfort Quite 15 headset...they doesnt work With only 1 AA (1,5v) any moore...but if I increase the voltage to 2.3---3..V it kick in and work, and the LED (Power on) lights up....??jarleiceman

author: jabramo
author_rank: Regular Contributor
timestamp: December 02, 2013, 10:42:26 pm
content: Have you tried hunting down the root cause in the headphones circuitry?If you want to go with a 2 AAA maybe you could consider something like thishttp://thumbs1.ebaystatic.com/d/l225/m/mIxtcSIBL1P2cvP50B50Dtw.jpgJust attach that to the headband and solder the wire's to the terminals of the battery holder.EDIT: Here is the battery terminal for the headphones

author: jarleiceman
author_rank: Contributor
timestamp: December 03, 2013, 03:08:21 pm
content: Thanks 2 U allIt was actually Place for a AAA inside (dont know if it effects the sound...)and I serial conected them, a litle super-glue...worked like a charme....but I give my left arm for the schematics for these.....

author: djococaud
author_rank: Regular Contributor
timestamp: December 04, 2013, 07:04:23 am
content: Hi,What about a small joule thief Psu ?I've played with these and I know they can be very small...I've used it to power leds goggles with an old "dead" AAA battery, very tiny and works like a charm !If you want a clean output, just add a capacitor on the output...

author: TheBorg
author_rank: Frequent Contributor
timestamp: December 04, 2013, 07:07:56 am
content: Quote from: jarleiceman on December 03, 2013, 03:08:21 pmCan't do much worse than this