Thanks Ron

Much appreciated, i always thought i had to add the coin cell batteries so one letter 3x 1.5 = 4.5v so with 5 letters i would need alot mre battery power. Newbie way of thinking lol. Would a 4xaa be also okay so for added battery life.

Peter

 

This is a rough drawing. You will remove the existing 1.5 volt coin cells. You will place in parallel all of the letters wiring where the batteries were in parallel. You will leave all of the existing switches ON. You will leave all existing resistors in place. You will add a battery source but only a 1.5 volt battery source and also add a switch.


Ron

 

Great stuff Ron

Thank you for the drawing that really made it easier to understand, one last question the cable i should use audio speaker cables look thick https://m.ebay.co.uk/itm/20-METERS-...074341&hash=item4aeb4c4da0:g:vbMAAOSw63FaKc3B

Can you recommend anything more suitable?

Thanks Ron

 

It will be too thick but also it is CCA (Copper coated aluminium.) I have never tried to solder this but I suspect the copper coating would disolve in the solder and you would be trying to solder to aluminium.

Ron.
The TS said in post 1 that each unit had three button cells in series so he would probably need three AA cells in series but he may also need to add an additional resistor as the resistor value in the units probably took into account the internal resistance of the button cells.

Les.

 

Hi Lee could you recommend what type of cable/wire i should use? So 3xaa would be suitable? also would i need extra resistors? If so what type? And where would i add them to the diagram Ron drew up for me?

Peter

 

yes as we know that some LED circuits explained examples from various projects: flashing LEDs, 220V LEDs and more

 

It will be too thick but also it is CCA (Copper coated aluminium.) I have never tried to solder this but I suspect the copper coating would disolve in the solder and you would be trying to solder to aluminium.

Ron.
The TS said in post 1 that each unit had three button cells in series so he would probably need three AA cells in series but he may also need to add an additional resistor as the resistor value in the units probably took into account the internal resistance of the button cells.

Les.

OMG, many thanks Les. Yes, 4.5 volts. Darn I read right through that more than once.

Yes, you want 3 AA batteries in series for a total of 4.5 Volts and thanks again to Les for seeing where I had this screwed up.

Yes, the speaker wire linked to should work out fine.

Ron

 

Thanks guys

So should i not follow your drawing? And go in a series? Abit confused now lol, also found this wire https://m.ebay.co.uk/itm/Silicone-W...hash=item283030766e:m:m-Y091jnth58rzuO_pfDmiw will this do?

Many thanks

Peter

 

Not quite as my drawing reflected only a single battery in the letters, not the three and I showed the additional batteries in parallel rather than seines. As to the wire? Just about any common hookup wire will work. You still remove the existing batteries, leave e ON and add your battery pack as shown but the added batteries are in series in pack. Still can't believe I screwed that up, sorry.

Ron

 

Thanks Ron

So would this battery holder be series? Still 3xaa batteries right? So does that mean the letters should be run in series or parallel?

Peter

 

Also would i need another resistor as Les stated? If so where would i put it?

 

Each letter has its own series resistor so no you need not add any more resistors. My guess is your battery pack which has 3 AA batteries will have them in series for a 4.5 volt output which is what you want. The letters are placed in parallel with their individual batteries removed. Each letter will have a + and - where the batteries were in it so you connect all the + and all the - together, that is parallel.

Ron

 

Ron

Alright i understand now i i thought you wanted to me to have everything in series but letters parallel and batteries series, so connect all the + from letters to the battery + and all the - from the letters to the battery - thanks guys i'll go order the stuff

Peter

 

Any further issues or problems let us know.

Ron

 

The 15 Ohm resistor is probably too low when used with 3xAA cells. They were likely relying on that fact that those tiny button batteries have a high internal resistance. A spec sheet says < 20 Ohms, which means it will be around 20 Ohms, especially after a little use.

So, if 20 Ohms is correct, the actual resistance is more like 35 Ohms. If you add one resistor for all 5 letters, it should be 1/5 of that or 4 Ohms. I would place a 4.7 or 3.3 Ohm resistor in series with the batteries and switch to avoid the chance of burning out the LEDs.

Bob

 

Hi Bob

Which should I add 4.7 or 3.3 ohm resistor? And should it be placed after the switch or before?

Peter

 

Another question would i be soldering to the top part where the switch is or to the part below it?

Peter

 

You connect at each letter on where the battery terminals were. As to adding a resistor it won't hurt. Worst case the LEDs will appear to be slightly dimmer and it would be a good way to go. I would, not knowing the current load, use maybe a 1/2 watt resistor. Try a 1/2 watt 4.7 Ohm and if they are too dim drop[ to around 3.3 Ohms as Bob suggested.

Ron

 

Thanks Ron

So im looking for a 1/2 watt 3.3k or 4.7k ohms resistor

Peter

 

I believe the coin cells you had in the letters were 1.5 volt so you would want 3 AA batteries in parallel. Batteries in series the voltage is added so 3 AA in series would be 3 * 1.5 = 4.5, not what you want. 3 AA in parallel would be 1.5 volts but offer more current for the longer run time. Let me make a little drawing and post it.

Ron

I thought in the earlier posts it was 3x coin cells per letter, so 4.5V per letter.

I think you DO want the 3 AA batteries in series, not parallel.

Edit: Sorry, I see there have been many posts since I looked and this w already covered.