dc dc converter with variable dynamic output - Page 1
Forum section: electronics / beginners

author: tarzan
author_rank: Newbie
timestamp: September 23, 2014, 12:13:09 pm
content: Hello guys, I am new here. I just want to know the possibility of creating such a thing or I am dreaming. these are the details without the unnecessary stuff. Basically I need to design:1- DC to DC converter2- You preset a range of wattage required at the output, for example 2W to 5W3- Using a potentiometer (a trigger potentiometer? like xbox I don't know what you call them) when you press it, the range goes from 2W to 5W or 5W to 2W (in analog or digital increments doesn't matter)4- At rest (when trigger is not pressed) the circuit is disconnected (I think the xbox trigger does that?)So is it possible to do it with off the shelf converters and adding components or is it something that need to be designed from scratch? Thanks guys.

author: Simon
author_rank: Unknown
timestamp: September 23, 2014, 12:21:26 pm
content: You need to post much more detail of what your trying to do. What you have posted make little sense.

author: tggzzz
author_rank: Super Contributor
timestamp: September 23, 2014, 12:25:54 pm
content: Quote from: tarzan on September 23, 2014, 12:13:09 pmSo you think that is a solution to your problem. You will get a better response if you indicate what your problem is.One specification that matches your current wishlist is a device that goes from 2000000V@1uA to 1uV@5000000A (i.e. 2W to 5W).

author: tarzan
author_rank: Newbie
timestamp: September 23, 2014, 12:32:43 pm
content: Ok guys sorry for not stating the problem very well. But I am not trying to design a dc to dc converter from scratch. Assuming you have a converter ready like this one:http://www.geindustrial.com/products/embedded-power/naos-raptor, this converter can deliver 0.6 to 6V. I need to add to it components that first specify your working range (for example 3.5V to 5V) and a trigger button which when not pressed output = 0V, when pressed output goes from 3.5V to 5V as set. I just need to know if this is possible with such a converter or I need to design a converter from scratch. I hope that was clear enough. Thanks.

author: Simon
author_rank: Unknown
timestamp: September 23, 2014, 01:07:19 pm
content: Quote from: tarzan on September 23, 2014, 12:32:43 pmsounds like you want a variable voltage regulator (LM317) with a push button on the output. Alternatively you can use a switchmode power supply.

author: sacherjj
author_rank: Frequent Contributor
timestamp: September 23, 2014, 01:09:55 pm
content: You would just need to design a circuit to work with the trigger pot to do 3.5 to 5V. Then use the switch (if present) to enable and disable either a physical (relay) or electronic (MOSFET?) switch. Alternatively, if you have just a pot and no switch, you might have to detect the resistance and disconnect output if it hits your minimum.This would be pretty easy on a linear regulator, like a LM317. You just need to hook up to the correct side of the pot so the reference voltage moves in the correct direction.Looks like Simon and I have the same idea. Yours popped up when I went to post.

author: tarzan
author_rank: Newbie
timestamp: September 23, 2014, 01:13:21 pm
content: Thanks guys for the suggestions. Problem with the regulator is that it won't allow me to use the 60A output limit of the raptor?

author: Simon
author_rank: Unknown
timestamp: September 23, 2014, 01:32:54 pm
content: you want to supply 60A ? then you need to use a very large SMPS with variable output.

author: tarzan
author_rank: Newbie
timestamp: September 23, 2014, 01:50:49 pm
content: Thanks again, I see the issue.If we ignore the setting the voltage aspect for now, and assume we are using a trigger pot for the converter to go from 0.6 - 6V, is it possible to implement breaking the circuit when the trigger is not pressed? If i can at least solve this maybe I can get somewhere first.

author: Simon
author_rank: Unknown
timestamp: September 23, 2014, 02:00:24 pm
content: First you need a circuit that provide 60AThis needs to have an adjustable output.Somehow however the circuit needs to be told what voltage to output needs to be compatible with your potentiometer which does not sound like a problem because more controls like the one you descrip are potentiometers and SMPS regulate their output voltage based on a couple of resistors or a potentiometer.For the off/on bit you need to either use a switch or use your trigger potentiometer to alter the reference voltage on the SMPS that will alter it's output and you will need some control circuitry that when it sees less than a certain voltage on the trigger pot cuts the power.

author: Seekonk
author_rank: Super Contributor
timestamp: September 23, 2014, 07:30:06 pm
content: First you say 2W to 5W, then 0.6 - 6V, and now it is 60A. If you actually wanted it to be constant wattage, a UNO driving PWM converter would be interesting. I have a solar power system and I use a UNO driving bug bulky transformers from old UPS. Hey its free, it works, but a little whinnnney.