Suitable parts for small model car

Hello all,

I am looking to install lighting into a model car (12cm x 5cm), photo below.

My questions concerns what parts (processor, LEDs, batteries, on/off switch) I should consider using bearing in mind I wish to keep the electronics size to a minimum.

The programming code I wish to use is LED lights

Some notes I have made:

  1. A standard 9V battery is much too large to fit inside the model however I see there are mini 9V batteries … image

  2. The smaller the battery the better. As only 2 or so LEDs need to be powered I assume the battery can have a lower voltage than 9V, but I just need it not to affect the brightness or the code I wish to use.

An extra question (not priority but of interest)

If I needed to add sound (eg siren), what additional components would I need and would it work with any suggested parts?

Thanks for taking the time to read.

Any tips or suggestions is greatly appreciated.


Would a small LiPo 3.7v battery fit? You can run an Atmega 328 or an Attiny directly from the battery. I powered an N-Gauge model loco with an 80mAh LiPo from HobbyKing.

Just be careful charging LiPo cells and don’t discharge them too deeply.


Adafruit 5V Pro trinket has an attachable Lipo charger and you can plug in a 3.7V Lipo. The entire package is a little bigger n' your thumb. Charges with USB cord.

Cheap, tiny and very handy. I use these little guys like jellybeans.

-jim lee

If it's only lighting, what do you need a processor for?
Even basic effect lighting could be powered from 3x AAA cells, and whether you use a processor or simple logic is dependent on the effects required.