steev

thanks audio guru and ANTE. u both helped me a lot thanks once again. :) i don't want to start another thread for my friends quiry.so iam posting here only. i hope u will solve his problem also. he is working on a ckt which drives 6 LED remotely.imean using a RF transmitter(35Mz) and receiver.function is like when transmitter pressed on 6 LED's mounted on receiver side will glow.receiver uses 3AA cells and transmitter 2AA. he connected 6 LED's in paraller.so as voltage is above 3v.they r glowing with enough brightness.now the thing is they consuming power(current) quickly. so he want to know is it possible to boost current like voltage using some charge pumps.so that the LED's can be driven for long time. i'll be waiting for u r replies thanks

thanks for the schematic. do this ckt need any overvoltage protection.imean diode across the output.

this looks ok to me.i'll replace R1 and R2 with 120,18Ohms resistors.(no VR1). then i think i'll get 3v output. what wattage do i need for those resistors? yes i know that.iam talking abt those maxim dc-dc converter chips.

thanks audio guru i got it.it takes exactly the amount needed. so i'll try lm317(as amount of current used is very low.i hope chip will stay coll.but i'll still use a heatsink) on more thing abt the step down dc-dc converter.it uses(most of them) inductors.so u think this cause any effect on the circuit we r connecting at the output. imean if the output is to a fm transmitter....

then how can i limit the current if i use lm317 regulator. as the source current is 2.5amp and transmitter draws 20-30ma(as u said).i think current shld be limited or else it might destroy my small transmitter. 2.5amp to 30ma

thanks ante ur too good man. one more help i needed here. iam connecting this power supply (3v 200ma from a 12v 2.5A lead acid battery) to a RF transmitter.is it ok imean as this circuit uses inductor this might effect the RF. so what is ur openion.is it ok to go with MAX724 or LT1074 or linear type regulators imean lm317,L200 etc

thanks ante iam also planning to design switching regulator only.but most them are using inductors.is there any inductorless regulator.(as i want to keep it as simple as possible) and i am unable to find schematic for MAX724 iam new to these circuits. can u help me with the circuit diagram. (i need to control (lead acid battery)12v 2.5amp to 3v 200-500mah) thanks once again steev

hello all iam trying to design a voltage regulator ckt which gives output of 3V and 500-700ma of output current. input is from a led-acid battery rated as 12v-2.5Ah on net i found below circuit which is for battery charger. circuit no-4 http://agendawiki.com/cgi-bin/aw.pl?ChargingCircuits but regrading this voltage regulation some one said and he shown me this link http://www.rowan.sensation.net.au/electronics/stepdown.html and another one suggested L200 based voltage regulator. iam really confused between these. can u help me.

after ur previous reply i did a small search on google for driving 4 leds using 3v dv supply.and i found one,its a voltage booster.upto here every thing is ok.but i dono how can i mix with another IR circuit(push on release off type) pls atleast guide me towars a good ckt thanks

i dono much abt designing a hybrid circuit.i'll be thankfull if can u make a such ckt design for me. and the LED iam using here uses 3vdc supply.(i used 2 AA cells to test them).i'll use MAX 4 LED's in series. so can u make a design for me. i'll be waiting for ur reply. thanks

amazing.thanks for ur fast reply. now i'll explain u in detail.as i said i want to drive 4 normal bright LED's remotely. requirement:-and the ckt(receiver)shld be such that it will drive 4 normal bright LED's. when i press the transmitter button and go off when i release it. i know remote operation can be done using either RF or IR. i choosed IR as it is easy. limitations for this ckt is,receiver shld be as small as possible using 3-4v power.if u have any such ckt pls let me know.

hi all iam trying to design a simple wireless circuit which can drive 3-5 brigh LEDs. after a lot of search i found this circuit http://www.aaroncake.net/circuits/irremote.htm it looks simple and very compact. but as i want to drive 3-5 LED's how much power i have to use and what components do i have to modify. and the operation shld be like LED's glow when i press the transmitter button and go off when i release it. pls help me in building it thanks