That's another thing I would need to consider, life expectancy, as these at some point would need to be changed, are there any holders (similar to light builds I suppose) that I could fix in to the granite, and then the leds can be changed easily and quickly. Also, could any recommend the best place to pick up the items needed? If anyone from the uk has pre build circuits I'd also be interested in those.

 

That's another thing I would need to consider, life expectancy, as these at some point would need to be changed, are there any holders (similar to light builds I suppose) that I could fix in to the granite, and then the leds can be changed easily and quickly. Also, could any recommend the best place to pick up the items needed? If anyone from the uk has pre build circuits I'd also be interested in those.

This is where you need to look at several LED and potential socket combinations including sockets which can have conductive grease like used on motorcycle connectors exposed to the elements, consider the elements (environment) a memorial stone is exposed to as well as battery charging in for example sun and shade. Most of the inexpensive garden variety LEDs fail within a year or two so consider quality materials including battery and charge system. While I have not bought a grave memorial stone recently I do know they can be pricey depending on what someone wants.

I think you are into a possibly good idea but I don't see a cheap variety of garden LEDs as a viable solution considering the application.

 

Mouser UK might be a source. Many but poor data on solar panels but they have the following.
One thought is CD74HC14E, 6 stage Schmitt inverter, some Cs & Rs followed by 6 ea. MPSA14TRE
LED drivers. 2 units will give 12 blinking, throbbing, pulsing LEDs. Out of time.

 

Use modern solar panels with a glass top. Old ones had a plastic top that quickly got sunburned. They cost the same.

 

Use modern solar panels with a glass top. Old ones had a plastic top that quickly got sunburned. They cost the same.

How well do they work on a snow covered headstone? How fast will dirt and grime build up on either glass or plastic?

Ron

 

Completely correct. And, depending on the power analysis, "re-purposing" a garden light might be the best way to power a prototype at low cost.

ak

Given that grave stones are intended to last a few years and given that none of the garden lights that ai have seen have lasted even one season, it seems that a better quality of every single element would be required.. That includes the very fragile solar cells and all of the wiring made as cheaply as possible.
And one more thing is that most folks will stay out of the graveyards at night.

 

And one more thing is that most folks will stay out of the graveyards at night.

The residents stay there as far as I know. Then too, maybe I really don'y want to know.

Ron

 

I have many Chinese solar garden lights. Originally they lasted for a couple of months.
I buy ones with a glass solar panel and I throw away the rusting Chinese Ni-Cad battery and use an American Ni-MH battery that does not rust away. I also throw away the cheap Chinese LED with its iron wires that also rust away and use European or American LEDs that do not rust away. Now my solar garden lights last for a few years.

 

Thanks very much for all your help everyone, I'll try to get a list together today from all the info you have given me and post it to see if I've missed anything vital. Highly likely given my limited knowledge.

 

Have a look here for garden ornament lights at CPC Preston uk..

https://cpc.farnell.com/search/prl/results?st=Garden lights&sort=P_PRICE

 

Right I've done a bit of searching and found the following

Thorlabs 2 pin LED Socket – Part No 8060-2 - £8.00
Mouser UK White LED - Part No 941-C513AMSSCW0Z0132 - £0.22p
RS Components Solar Panel – Part No 179-3740 - £2.40
RS Components NiMh Rechargeable Battery – Part No 777-0374 £14.22
RS Components Harsh Environment Wire – Part No 359-677 - £13.01
Waterproof Junction Box – Undetermined due to not knowing PCB size needed.
RS Components Conductive Grease – Part No 918-5028 - £20.46

I'd imagine some of those parts may not work as I have no idea about what needs to charge what at what voltage etc.. or if its the right kind of LED, you could call it an uneducated guess!
I have not accounted for the PCB. I have no idea if this will need to be custom made, or if there is something out there I can buy of the shelf. Any pointers on this side of things would be great.
And I would like to thankyou again, you have been very helpful to a complete stranger coming out of the blue picking your brains!

 

After reading another website it seems randomness with electronics is difficult, fading also seems difficult. Put the 2 together and it becomes very difficult. Given all the factors I need such as turning on when dark, I'd also like to possibly add a manual switch in there, if you wanted to see them on and it was not dark, you'd have a bit of a problem. The randomness, the fading etc.. do you think it would be worth passing the PCB side to electronics company? who can design the circuit and build it, so I just need to connect the battery, solar panels and LED's.

 

Have a look at Cpc site for components before you get it from RS,.. For random leds it would be easier with a micro or a 556 timer chip, or Cd4093, Cd4017 counter.

https://cpc.farnell.com/browse-for-products

 

Selecting parts at random will cause quick failure.

The battery has five AA cells and is huge and is very powerful. When fully charged it can burn out the LED instantly or with an added electronic circuit cause one LED to fade on and off brightly for 130 hours. You need a battery that is 32 times smaller which will cost much less.

The solar panel is also much too large, too powerful and too expensive for what you need.