Help making a "timer" for a flashlight.

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vestureofblood
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Help making a "timer" for a flashlight.

Hi all,
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This is an extension of one of my UV projects. I need to be able to make a timer that will shut the light off after a certain amount of time. Got any ideas?
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A distant second to this would be a display that showed how long the light had been on for starting when the switch was hit, but the above would be much better Smile
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Thanks

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Lightbringer
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Needs to be small, I take it?

Dunno if it’d run on as little as 3V, but a JFET timer (eg, 2N3819) would be simplest, its output driving a bigger (MOS)FET.

Else a 7555 IC in monostable mode.

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stephenk
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Interested in a solution (especially if it works with ConvoyS2+, L6, or BLF Q8). Would be useful for solo light painting!

mattlward
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I would think that a 555 variant would have a simple enough circuit to make it fit in a smallish light. UV does not take that much current, maybe a tiny fet to feed 2 7135’s for around 700ma?

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The Miller
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How easy must it be to change the time?
Couldn’t a programmer add a mode like this to Narsil
Ramping, modes and timed on
Select timed on starts in time select (a click for a minute) and after 3 seconds no click for time ramp to select brightness
Just thinking out loud here.

vestureofblood
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Lightbringer wrote:
Needs to be small, I take it?

I have a little room to work with. I will go in a 2× 26650 size light.

The Miller wrote:
How easy must it be to change the time? Couldn’t a programmer add a mode like this to Narsil Ramping, modes and timed on Select timed on starts in time select (a click for a minute) and after 3 seconds no click for time ramp to select brightness Just thinking out loud here.

I considered having it work like a turbo timer or similar. That would be better than nothing, but I would prefer that a novice be able to change timer without too much trouble.

I wish I could make it be something like a miniature one of these that was in the end of the tail cap Smile
https://www.bedbathandbeyond.com/store/product/lux-spring-wound-timer/10...

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Lightbringer
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vestureofblood wrote:
Lightbringer wrote:
Needs to be small, I take it?

I have a little room to work with. I will go in a 2× 26650 size light.

I considered having it work like a turbo timer or similar. That would be better than nothing, but I would prefer that a novice be able to change timer without too much trouble.

A 26650 host with a side-clicky, you could replace the switch with a pot and have it go, say, from 0-3min.

In the driver, sense an analog voltage and count down accordingly (like a light/dark thingy in a toaster). With a separate timer circuit, that’d be the resistor controlling the timer.

Or w/o a side-clicky, it might be possible to drill a hole with a really small pot. I’ve seen 1/8” shafts on pots barely bigger than that.

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prepro
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Lazy-R-us
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I think your best bet would be to get with one of the firmware gurus and see about incorporating a real time clock to talk with the ATTiny processor. Once the processor has an accurate clock, you could get a mode for both delay off and delay on, with the delay selected by some number of clicks perhaps. Adafruit has several different options.

Alternatively, simply bringing out the pins on an e-switch light to a wireless remote would allow you to control a light that way., Adafruit has these

Or you could go full bore crazy and set up a local Wi-Fi hot spot and run a Spark Photon from your phone controlling any number of drivers with different colors or tints of light. Spark Photons.

Lazy-R-us