Electronics > Beginners
Using a zener with variable input and led - brain freeze
<< < (3/3)
exe:

--- Quote from: digsys on July 26, 2019, 11:21:03 am ---I have never used Leds that draw more than 1mA for full brightness. They cost bugger all more.

--- End quote ---

Interesting idea. I recently bought green leds, they were already bright for me at 0.15mA. Just for fun I tried to see what's the minimum current that would still make it visible. It was 5-8uA at daylight.

I wonder which color requires less current. It's not just about brightness, but also eye sensitivity is different to different colors.

PS I also have red leds that are barely bright at 20mA.  :-// . These are new, I think it was this model: https://www.tme.eu/nl/en/details/l-424hdt/tht-leds-3mm/kingbright-electronic/ I wonder how this is possible and what's the application for such low brighness? The efficiency is super-low, I only bought them because I didn't know how much brightness I needed.
aries1470:

--- Quote from: PA0PBZ on July 26, 2019, 11:52:41 am --- (Attachment Link)

--- End quote ---
Thank you for that schematic. So, what diodes are you using? would those be two "normal" diodes? since I didn't see them as zeners or schotcky.
If so, would signal diodes also do, i.e. 1N4148? Since I am going to use very minimal mA  ;D
For the NPN transistor, I have available for easy purchase the following:
(Yes, I will be doing two versions, one THT and one SMT),

It will not dramatically increase the cost, and would help "debug" where a potential problem may be when the other people do not have a basic understanding of electronics - and don;t need to either. So this will help a lot :-)

ON Semi KSC1009YTA - THT $0.074AUD - 100pcs - $7.40AUD B160V / E140V <- Will be going for this ;)
ON Semi BC546BTA - THT $0.116AUD - 100pcs - $11.60AUD B80V / E65V
ON Semi BC546CTA - THT $0.071AUD - 200pcs - $14.20AUD B80V /E65V
ON Semi KSP06TA - THT $0.139 AUD - 100pcs - $13.90AUD B80V / E80V

ON Semi MMBTA06LT1G - SMT $0.108AUD 50pcs - $5.40 B80V / E80V
FMMTA42TA - SMT $0.067AUD 50pcs - $3.35 B330V / E300V  <- Will be going for this  ;)
Infineon SMBTA06E6327HTSA1 - SMT $0.052 100pcs - $5.20 B80V / E80V

Edit:
Added more SMT options.

Edit 2:
Link was correct for FMMTA42TA, but had MMBTA06LT1G in its name. Oopps, sorry.
Thank you to everyone that has replied, as I was not aware of this option.
aries1470:
Hi guys,

Just want to confirm if all will be okay using the following:
2x 1N4148
1x  KSC1009
1x 10K Resistor
1x 100 Ohm Resistor
1x LED

will be assembling on a breadboard.
Does anyone see any issues assembling as per image from @PA0PBZ?

Thank you.
Zero999:
It looks good to me. The current regulation in real life, probably won't be as good, as the simulation, but it'll certainly be much better than the zener circuit.
Navigation
Message Index
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod