Electronics > Beginners

Using varistor instead of pot. to autom. adjust res. in joule-thief for bat.life

<< < (8/8)

Distelzombie:

--- Quote from: JS on July 11, 2018, 05:43:01 pm ---  I'd just pointed out some inefficiency spots on the design, you should get it to work and see if efficency is a problem, maybe you are at 60% efficiency and your battery life is enough, so you don't need to mock around any longer, you won't get to 98% with this, efficiency in low voltage is quite low, as a small drop represents a big portion of the total supply.

  To be able to optimize a design you need a lot of things, lot of measurements and knowledge of basic devices are two of them. I can't make measurements and I don't have the time to search for your part, I can suggest where to look for.

JS

--- End quote ---
Yea, but you're contradicting yourself and not answering questions. Here:

--- Quote from: JS on July 11, 2018, 03:16:38 pm ---I don't know if it would work in that circuit as it is, probably not. Of course there are other specs to watch for, you don't need any mosfet with low rds, but the mosfet you pick should have low rds.
--- End quote ---
And I explicitely said: "Please answer all questions.", because I knew you wouldn't do that. This is really frustrating. How am I supposed to even start? It actually sounds like you're not knowing much more than I do.  ;D

But thanks for the help you've done so far :)

BrianHG:
I'm curious as to why no one has recommended trying a slow CDS photocell held up to the LED, working on top of your existing design.  Since this type of photocell acts as a true pure resistor, as the battery drains and the led gets slightly dimmer, the CDS photocell will be wired to boost the transistors turn on current.  With this you get the same circuit, and an almost regulated brightness, though, photo cell placement and initial calibration may be touchy, it may be interesting to experiment with.

JS:
I could do the design for you if you give me the specs, that would take me some time for which I charge a fee for, I'm pointing you in what to look for, I haven't seen measurements results neither run the sim to make better suggestions. I'm not contradicting myself, drop in replacement of a BJT for a mosfet doesn't usually work, but a circuit using a mosfet tends to be more efficent than one using a bjt. I've also said that bjt efficency is probably good enough, and I think you only need to address the brightness stability, that would make a viable product, all the rest is for later optimization, I don't think you need to learn all about mosfets to get this running.

JS

Navigation

[0] Message Index

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod