One for the electronics experts in the Collective.

[slim_boy_fat]

Slim Boy ..why don't you use 'ordinary' leds that take hardly any currrent (20ma or so) and can be easily controlled for brightness even with a battery supply ... in fact ....just remembered..... I've got some 3 colour leds that change colours automatically and use very little power ...pm me your address and I'll send you a few... Gerry

Most kind, can I keep your offer in reserve? Colour changing might be very effective. I'll probably do a dummy run with what I have to check brightness, the shell is thicker & more robust than I expected.

It will need a big heatsink on the back or it will burn out quick if run at full power.

My thinking was to hot-glue under the terminals to allow a small air gap between the LED(s) and shell - do you reckon it'd need more than that?

 

[CoValent]

Those look to be a good idea/solution, but although they're on offer at £1 for a pair the nearest B&Q is 40 miles away and they're not available to order online. Ah, well.......

How many lamps do you need? Send me a PM with your address and I'll drop them in the post. I checked one on the bench just now. See attached pictures, the brightness didn't vary between 7, 12, and 16 Volts but as you can see the current increased at the lower voltages, which tells me that these lamps have a nice little inverter built in. Sorry for the crappy display - the power supply display is strobing which confuses the camera. Left to right is 7 Volts/156mA, 16Volts/60mA, 12V/82mA

 

[RaceDiagnostics]

My thinking was to hot-glue under the terminals to allow a small air gap between the LED(s) and shell - do you reckon it'd need more than that?

The ones from banggood in your link will melt the hot glue in no time, I think they are too powerfull for what you need, look for an alternative as suggested above which will be a better solution.

 

[slim_boy_fat]

How many lamps do you need? Send me a PM with your address and I'll drop them in the post.

Very kind, you're a gent. I think those will be easier to connect to the power supply too, so win:win.
PM incoming.

 

[slim_boy_fat]

The ones from banggood in your link will melt the hot glue in no time, I think they are too powerfull for what you need, look for an alternative as suggested above which will be a better solution.

TBH, I never considered the heat output, I only powered a couple up to ensure they lit. I thought LEDs were cool running?

 

[sako243]

I thought LEDs were cool running?

Compared to other lighting sources.

 

[eSCHEn]

Those 10W ones get very hot at full tilt. Limited to 700mA they're not any less bright really and barely get warm.

 

[eddie49]

Hang on a minute there, am I missing something??
That £2.38 little widget is a PWM that can handle 8 amps at 12 volts??
And this one will handle 30 amps for £5.23!
Can I put 2 in parallel and manage 60 amps ? (carefully!)

@rtcosic, as WorkshopChris said, two 30 Amp PWM controllers in parallel will not work, but you can even get a single one with a 60 Amp rating:

https://www.ebay.co.uk/itm/DC-10V-5...troller-CW-CCW-Reversible-Switch/163679865809

These controllers are intended for speed control of brushed DC motors, which provide a resistive and inductive load. I am not sure what electrodes and an electrolyte bath provide - probably resistive and maybe capacitive.
This paper implies that PWM-controlled electrolysis is possible:
https://waset.org/publications/1068...nt-of-pwm-controlled-water-electrolysis-cells
You could get one of those controllers and try it ..... maybe a small inductor in series would be a good idea.

 

[CoValent]

So I can replace my ugly bulb box (resistance box) current 'controller' on the output of my 240 V AC > 12 V DC 8 amp power supply liberated from an ancient PC that I use for electrocleaning and electroplating??

I think a cheap PWM controller would work very well in your application. Why are you looking for a 60A constant current source if your PSU has an 8A rating, though?
Something about the numbers doesn't look right. Electroplating at 12V with a current limit of 60A implies a maximum input of 720 Watts to your tank. Confused dot ie

 

[rtcosic]

@rtcosic, as WorkshopChris said, two 30 Amp PWM controllers in parallel will not work, but you can even get a single one with a 60 Amp rating

I think a cheap PWM controller would work very well in your application. Why are you looking for a 60A constant current source if your PSU has an 8A rating, though?
Something about the numbers doesn't look right. Electroplating at 12V with a current limit of 60A implies a maximum input of 720 Watts to your tank. Confused dot ie

I updated my post in the other thread trying to explain why I thought I understood why PWM isn't suitable.

I was looking at control of 60 or 90 amp current as I had rebuilt a rectifier used in conjunction with a buzz box arc welder in the past.

However even this has been overtaken as the intended recipient has been given a 50 amp 240v AC > 12 v DC power supply.

 

[CoValent]

Ah, right. I hadn't realised there was another discussion running in parallel.

 

[slim_boy_fat]

Sorry lads, forgot about this. I found the chargers I thought were 'spare', in fact weren't....torches, phone(s) etc] I tried an LED at 6V and it lit [at about 50% brightness, not surprisingly ] and didn't get nearly so hot, but any power supply below that didn't light them up.

So I'm wondering if they'd operate off something like this, would be more simple and straightforward?

Mr Router could make a recess in the oak base to accommodate it.

 

[slim_boy_fat]

A small update. Firstly, a big shout out for @CoValent who sent me 2 x twin packs of those bulbs in post #22, which arrived today.

Today, I got myself out to the shed - constant rain being driven by a strong wind all day, much like most of yesterday but I got the diesel heater going [yes, really! ] and set to 'multitasking' .

First off, I gave Gerry's bulbs a quick blast to see if they accepted power from my 2 > 12V DC output power source. It was set to 8V from previous use, so I used that - no problem. Setting them aside, Iwent back to the LEDS ex China. They didn't ignite until 6V so I left one on at that and as no discernible heat was felt after a few minutes I left it going at that....after 3 hours it was the same, so I upped to 8V and within a short time [based on the tried & tested 'finger tip' temp sensor ] it was hot enough to burn skin, so 6V with these would be the optimum feed.

During this time I had been working on the red squirrel feeding table and have made good progress, in fact I hope to get in finished tomorrow - I'll post in the "Stuff I have made today" thread when appropriate.

Back to the bulbs and I jury-rigged Gerry's contribution in the same fashion. They ignited at 2V and at all other feeds, although they got just 'warm' towards the upper settings after a good while, so definitely better.
Next will be to repeat the test(s) to see which emphasise the opacity of the shell best - I'm still favouring Gerry's for this too. Time & testing will tell.

It looks also that Gerry's will cope better with a battery pack for power and I'm leaning towards this as it'll mean total independence from tethering power chords, then I'll just fit a 'classy' on/off switch in the oak base.

By this time a tidy up was in order and inside to prepare tea, in advance of the Belgian F1 qualy highlights.

Very sad news about the young F2 driver Antoinne Hubert who tragically died of injuries sustained in an horror crash.

 

[RaceDiagnostics]

If they are spare, run an ebay one at full voltage for a while and see how long it lasts without cooling.

Edit, put you sung glassed on first.

 

[slim_boy_fat]

Well, they say if you want to hear God laugh, make a plan.

Just before I was getting organised for kip, a sharp crack and I spotted that a shelf was trying to become floorboards [it's amazing how heavy dust is ], so it spent the night propped up like so....



and today I have this...



Shelf in shed having been painted [and a strengthening lip added], holes drilled into brick walls for side bar supports and will be painting again tomorrow. Oh, well......

It could have been worse, I'd not have been happy if it had taken the TV out.

 

[slim_boy_fat]

Back to the conch shell light/ornament, today I've been playing with the LEDs again, this time connected in parallel and powered by the 12dc charger, jury-rigged as a test to see if they heated up after a while. Pretty it ain't but it was just a test.



Seems to be successful, after 45 mins or so they were quite cool still. Now to make a 'proper', tidy job of the wiring and decide what and how I'm going to mount them on for placing inside the shell, so they don't rumble about with shell movement.....

Also made, as a 'proof of concept' a small third hand, useful for placing & holding small parts when soldering [btw, I'm impressed with the Parkside soldering station ] or even welding. Shank is currently a six inch nail, but I may make a Mk11 in due course.



Slow progress, but progress never-the-less.