Electronics info needed for RFM mod

[Eddie]

Ok so its another RFM thread but not really as the info that I am inquiring about if answered, can help others who want to mod their machines no matter what type.

On the page that I linked to, part way down there is a mod about installing LEDs into the martians eyes.

Pinball News - First and Free

The writer refers to the LEDs as being wired in Series and using a 3k3 resistor

My questions are these

1 When connecting the LEDs is it Anode wire to cathode wire?

2 When adding the resistor which lead should it go to and where on the lead?

3 Does RadioShack sell 3k3 resistors and if so would anyone have a part number?

4 Which lead goes to the positive on the coil or does it matter?

5 If I were to run a series of 10 leds (For my topper Project) what would be a simple battery or power source and what type of resistor would I need? thx

[garfield]

Hi Eddie,

Answers :

a) You wire the + lead (anode) of the first eye (LED) to the 80V.
b) Then you connect the cathode of the first eye to the anode of the second one.
c) Then you connect the resistor to the cathode of the second LED.
d) Finally you connect the loose end of the resistor to the 0V

I would add a potentiometer of say 10K linear to the whole setup. (just a little one), so you can regulate the brightness of the eyes. If that turns out to be unsatisfactory, use a resistor of say 2k2 in conjunction with the potentiometer.

Basically it doesn't matter where you add the resistor. It can be first, or in between the leds or a the end. You just have to make sure the Anodes of both leds are connected on the plus side of the voltage, else they don't work.

By the way, if you manage to wire them the wrong way around, don't worry, they just won't light up, but no harm done.

3) Every electronics joint sells 3k3 resistors.

4) Yes it does matter, see above

5) Well typically a LED has a Voltage step of 1.2 Volts. So if you would put them in series, you need a supply of about 12V (without any resistors)

If you pair up the anodes and the cathodes, I would use a potentio meter of say 1K and add a resistor of 100ohms in series with the pot and tune in the pot to the desired LED strength. Then you can use a battery or any powersupply.

By the way, A LED that is pumped up too bright, slowly dies out, so be careful with the potentiometer.

[drcrippen324]

or you could buy a cheap set of led fairy lights from ebay and place them in to give a chasing pattern with all the electris taken care of like i did with my betty topper

[Sid]

or you could buy a cheap set of led fairy lights from ebay and place them in to give a chasing pattern with all the electris taken care of like i did with my betty topper

and doc sure knows his stuff when it comes to fairies!

[Eddie]

Help!!! Can anyone find a 2mm ceramic Led vendor online? Maplin has them but I cant seem to be able to order anything from them?

I cant find any U.S. online vendors that carry them either!!!

Maplin Standard 2mm Ceramic LEDs

[rubberratt]

and doc sure knows his stuff when it comes to fairies!

LOL

Sorry Dr. C I LOL'd
(green suit snap)

[daverob]

Help!!! Can anyone find a 2mm ceramic Led vendor online? Maplin has them but I cant seem to be able to order anything from them?

I'm not sure that Maplin's website is set up for international orders. You might be able to order from them if you phone them.

If you can't find a more local source, send me a PM and I can get them and send them on to you.

[hanabi]

I also use Maplins regularly, and can help if you get stuck Eddie,
just drop me a PM