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Topic: IR LED - Which would use less power? (Read 3449 times) previous topic - next topic

Boardburner2

a CSS555 would be much better for consumption.

More work for the op to understand though.

Wawa

#16
Mar 29, 2016, 11:46 pm Last Edit: Mar 30, 2016, 12:05 am by Wawa
a CSS555 would be much better for consumption.
As said, little output current (pin3) available at low (battery) voltages.

Only the 'discharge' pin of a cmos 555 can sink enough current to drive/modulate an IR LED at low supply voltages. Example attached is a continious mode 5meter curling game 'beambreak' ~38kHz IR transmitter I designed some time ago. Works on 2x AA for a looong time. LED/resistor to the left is a battery indicator, and is not needed to function.
Leo..

daveyjones

That's what was suggested.  (FWIW the only 555 I have here is a cmos version)

Although, after reading today; I ordered up a few 4541's they seemed more like something that was usable for the long duration.

----

It's a project for my uncle..
Dish recently forced us to upgrade satelite receivers.  This new receiver shuts off after 4 hours of no use. (there is a setting, which is currently 'disabled', but it still goes to sleep).  He tried dealing with them but he got nowhere dealing with dish.  It was trivial enough to build a small thing to send the "power on" code every x hours. (it's working fine) --I just want to reduce the power more so it can last longer on batteries.  (we want it to stay on, so the dvr can record things; we don't want enough tv that 'normal use' would keep the  receiver watchdog from going to sleep...)

Wawa

This new receiver shuts off after 4 hours of no use.
Understood. Bloody nuisance compulsary power savings "feature".
My Samsung TV also does that e.g. when I'm watching a long movie.
"Press a button within 1 minute, otherwise I will enter standby" Grrrr.
Or when I turn my PC/media player off: "You have unplugged the HDMI cable".
I wonder if the people why design those things ever watch TV.


Can't you use e.g. a Nano and a 5volt phone charger with micro-USB lead.
A phone charger runs on fumes. Batteries are expensive
Sleep the Nano if you want to, or use it also for something else e.g. temp display or fancy TV background lighting.
Leo..
 

Boardburner2

#19
Mar 30, 2016, 09:56 am Last Edit: Mar 30, 2016, 10:08 am by Boardburner2
As said, little output current (pin3) available at low (battery) voltages.

Only the 'discharge' pin of a cmos 555 can sink enough current to drive/modulate an IR LED at low supply voltages. Example attached is a continious mode 5meter curling game 'beambreak' ~38kHz IR transmitter I designed some time ago. Works on 2x AA for a looong time. LED/resistor to the left is a battery indicator, and is not needed to function.
Leo..
It was not for driving a led, the output drives a latch to switch on an arduino supply which then drove the led before switching off the latch.

Although, after reading today; I ordered up a few 4541's they seemed more like something that was usable for the long duration.

The CSS555 is better for battery app, same quiescent current but works down to a couple of volts.

Wawa

Also known as the ICM7555 (Maxim).
Leo..

daveyjones

Understood. Bloody nuisance compulsary power savings "feature"
What frustrates me the most is there is an option in setup to disable the feature; but it doesn't work... and dish sees no reason to a) believe me, or b) fix it.   That is even more frustrating. Reminds me the days of cable tv...

My Samsung TV also does that e.g. when I'm watching a long movie.
"Press a button within 1 minute, otherwise I will enter standby" Grrrr.
That is annoying as heck... I got really frustrated to watch some show I wanted , only to see the screen saver message "Your receive has turned off to save power, press 'ok' to turn back on" -- Why it can't turn back on when it sees a channel change is beyond me.  Luckily periodically sending the "on" Ir sequence doesn't alter what is on tv (no messages) and is not a toggle...

Can't you use e.g. a Nano and a 5volt phone charger with micro-USB lead.
Yes, I can; in fact I even picked up a 5v charger from the thrift store (I love that place for finding reusable electronics) but I decided to use this opportunity as a learning exercise (stretching the power).  That and my uncle doesn't want another cord.. (neat freak of sorts; but he has always pushed me to try harder, so this may be one of his pushes to get me to learn more...)

A phone charger runs on fumes. Batteries are expensive
Initial version is a promin running off 3 AA batteries, this should last a good long time.  Next version will be a rechargeable battery  (like an 18650)

Sleep the Nano if you want to, or use it also for something else e.g. temp display or fancy TV background lighting.
It is awake for such a short period of time; most of the processing time is taken up staying asleep.
Every few cycles, it checks the battery voltage, if it dips down too much; it will start flashing the onboard led occasionally.
Otherwise it's a waiting game for 90 minutes to pass, send signal, wait for 90 minutes to pass... If I can cut down on the power it's using in sleep mode by flipping the power off; that would save more power...

re the 555 -- I only have 1 cmos555 here; and all I could find, schematic wise, involved using two 555's or two 556's with a 3rd chip to achieve 90-120 minute delays.  The 4541 seems to be low power & more capable of long delays.  (I did order up a couple of 555's as well to try to  put together both circuits & try to see which is A) easier, B) smaller, C) better in power usage...

If you would suggest a good way to use a 555 for 90+ minute delays; please point me to it -- but so far, all I've read either says the 555 is not capable of those delays or I have to combine two...

Thanks for the ideas!

(I also squeezed in a ucurrent PCB & will build a couple over the next few months as time/money permits; also as a learning experience; but I may end up with an extra....)

Wawa

#22
Mar 31, 2016, 12:21 am Last Edit: Mar 31, 2016, 12:21 am by Wawa
In the eighties, before everything was done with a micro, I would have used a CD4060 (74HC4060) for this job. RC clock time set to the IR send time, and a diode 'OR' port to block the remaining time of the ripple counter for the delay time.
Leo..

Boardburner2

What frustrates me the most is there is an option in setup to disable the feature; but it doesn't work... and


I have a very similar problem with a sky tivo box.

The magic eye gets its power off phantom on the distribution coax, output 2.

Power has to be enabled in software but will not work.
(Its not the distribution amp BTW. Thouroughly tested).


daveyjones

You seem tech savvy, might like to consider one of these.
Use sleep mode then de solder the usb and led once it's working
Funny you should suggest that -- I tried an attiny85 but had some timing issues that I couldn't get past.  I ordered up a digispark board as well as a resonator to see if that'd get the timing right.

thanks for the idea, I was just a little bit ahead of you ;-) (I ordered them this morning)  Worst case is I have a small board to do something with later, best case, it works & I save some battery...

The pro-mini (or mini-pro) doesn't have a usb, and I desoldered the 'power' led... but I think atmega pulls more than the tiny... I thought about desoldering more, but then I figured I should start the other way "bare bones" and work up. (I also ordered a dip atmega328p, just in case)

Thanks again! 

Boardburner2

Typo i meant the led, attiny85 does not have usb either.

What current does it draw ?

daveyjones

An attiny85?  Not sure, haven't gotten it yet.
According to data sheets.. about .7ma @ 1mhz, .2ua in sleep mode.
I do not have a good way to measure it tho.  I know it will be slightly more with the IR being activated...

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