Author Topic: LED Lighting a Trimphone dial...  (Read 1206 times)

Offline tubaman

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Re: LED Lighting a Trimphone dial...
« Reply #60 on: August 11, 2019, 06:15:36 AM »
That has come out stunningly well - I'm very impressed!
 :D

Online countryman

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Re: LED Lighting a Trimphone dial...
« Reply #61 on: August 11, 2019, 08:36:04 AM »
Nice job!
Interesting that the LEDs are bright enough with just one 1.5V alkaline cell. Most small LED applications use 3 cells (4.5V).

Online twocvbloke

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Re: LED Lighting a Trimphone dial...
« Reply #62 on: August 11, 2019, 08:50:46 AM »
That has come out stunningly well - I'm very impressed!
 :D

Thanks, I'm still loving how it looks...  ;D

Nice job!
Interesting that the LEDs are bright enough with just one 1.5V alkaline cell. Most small LED applications use 3 cells (4.5V).

Thanks again, the joy of the Joule Thief is that it pluses the LEDs on and off, as it builds up a charge in the inductor, and the transistor switches on or off (I forget which it is) and the charge goes out to the LEDs, illuminating them at a decent level, and as it's so fast, the human persistence of vision doesn't see the flicker, so it looks like it's always on, when in reality it's switching them on and off at a rate of between 15-50kHz, and doesn't need 1.5v, it can go as low as 0.5v and it'll still operate... ;D

Online countryman

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Re: LED Lighting a Trimphone dial...
« Reply #63 on: August 11, 2019, 10:54:58 AM »
Thanks for that info, now I also got what the induction coil is for! :-)

Online twocvbloke

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Re: LED Lighting a Trimphone dial...
« Reply #64 on: August 11, 2019, 10:57:17 AM »
Thanks for that info, now I also got what the induction coil is for! :-)

I linked to the video where I took inspiration from in an earlier post:

http://www.classicrotaryphones.com/forum/index.php?topic=21609.msg229697#msg229697

Clive details how it works and how to assemble them, they're quite easy circuits to make... :)

Online twocvbloke

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Re: LED Lighting a Trimphone dial...
« Reply #65 on: August 11, 2019, 12:49:41 PM »
Thought I'd give the joule thief circuit a probing with my oscilloscope, and it produces a nice picture, but given the drifty nature of my scope (bought spares or repairs off ebay, so, not reliable!) it was way off the numbers, so poking the circuit with my multimeter, it seems the LEDs are being lit at a rate of 7.87kHz, lower than I was expecting, but still plenty power to give them a nice illumination level... :)

Offline HarrySmith

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Re: LED Lighting a Trimphone dial...
« Reply #66 on: August 11, 2019, 06:38:50 PM »
Awesome! That came out great. Thanks for the step by step posting so anyone in the future who wants to give it a try will be able to.
Harry Smith
ATCA 4434
TCI

"There is no try,
there is only
do or do not"

Online twocvbloke

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Re: LED Lighting a Trimphone dial...
« Reply #67 on: August 12, 2019, 05:43:16 AM »
Thanks, it took a while for me to get it together properly, but it is certainly something I'm pleased with,I'd be interested to see others having a go at making their own, and maybe have it take off as a way to revive the appearance of the humble Trimphone... :)

Offline FABphones

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Re: LED Lighting a Trimphone dial...
« Reply #68 on: August 12, 2019, 07:18:08 AM »
I'd be interested to see others having a go at making their own, and maybe have it take off as a way to revive the appearance of the humble Trimphone... :)

Well you've already given me food for thought with your results. I have several ideas re the illumination and have gone through how to power it via the phone with my ex-British Telecom engineer :) who very matter of factly explained how to do it and has agreed to help me out.

...I'd already had another idea to try out too. And this fits in with another project I currently have underway.

Plus I have a box of various coloured Trimphones to practice on and make good.

Just need to set aside more time. So many projects in hand.
A collector of  'Monochrome Phones with Sepia Tones' - and a Duck!

* Vintage Phones - 10% man made, 90% Tribble *

Online twocvbloke

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Re: LED Lighting a Trimphone dial...
« Reply #69 on: August 12, 2019, 07:43:11 AM »
I've been thinking about line-powering the LEDs despite having the joule thief, I'm trying to learn about how to use Zener diodes as voltage regulators to clamp down the ringing, on and off-hook voltages, but it hurts my brain, I have to visualise stuff in order to try and understand it, but Zener diodes are one of those things that my mind just won't comprehend...  ;D

And I know what you mean about many projects, I have a few other LED things on the go, I just haven't gotten round to finishing them off as I've kind of overloaded myself with them...  :o

Online twocvbloke

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Re: LED Lighting a Trimphone dial...
« Reply #70 on: August 12, 2019, 02:56:13 PM »
Just thought I'd add this, these white LEDs have been running on a "dead" battery for a week now, and only in the past few hours has the brightness of them noticeably reduced, but at 0.42 volts, they're still illuminated visibly, so there's plenty hope for the dial's Joule Thief setup...  :)

Though at that voltage, if the battery pack is knocked and briefly disconnects the battery, there isn't enough power to restart the oscillation, so needs to allow the voltage to recover to 0.48v before it'll restart by itself on this particular one (this happens to be my 2nd attempt JT, and so far is the best one!!!)...

Online twocvbloke

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Re: LED Lighting a Trimphone dial...
« Reply #71 on: August 14, 2019, 07:12:42 AM »
Seems the battery ran out (well, there's still a slight "barely working tritium tube" kind of glow there), but I think I know why, the more turns of wire on the inductor, the more current is drawn from the battery, and the faster the battery drains, and I put a fair ol' amount of copper on the inductor, so once I'm done doing important appointment things today, I'll have another go at the coil on this, and also find another AAA cell, or something similar & small... :)

Offline tubaman

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Re: LED Lighting a Trimphone dial...
« Reply #72 on: August 14, 2019, 08:26:41 AM »
If a 'dead' cell lasted for over a week I wonder how long a new one would keep it going?
Anyway, it sounds like a fun way to get the most from a cell that would otherwise only go for recycling.
 :)

Online twocvbloke

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Re: LED Lighting a Trimphone dial...
« Reply #73 on: August 14, 2019, 09:01:41 AM »
Well the dead cell on the white LEDs is still going, but the one on the dial was new, so a tad disappointing that it has already run out, it just depends on how efficient a coil I can make to get decent brightness and long runtime, still experimenting with them until I get the hang of it... :)

Online twocvbloke

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Re: LED Lighting a Trimphone dial...
« Reply #74 on: August 14, 2019, 01:30:17 PM »
I decided to take the coil from the white LEDs and stick it onto the dial, as that one seemed to be a better one, and also changed the battery (which I think is also used as it's already down to 1.1v), so the dial's lit up again, for how long, who knows... ;D

I probably should test the current of the output from the coils when i wind them, try and find a sweetspot as at the moment it's all guesswork, not helped by the fact I have differing ferrite toroid sizes which may also have an effect on power output...  ???