Excellent. I can have my experiment paused at any stage by just cover and lock the project box. All the wiring and components are undisturbed. Open the box and the project can be continued. Now, I can have my hardware “saved” and “opened” just like the software codes.
The current electronics are not robust enough. In moving the components over to the new housing, things are coming apart, soldered connections are failing, etc. There’s not really enough space in the box so everything’s crammed in and nothing has any strain relief so the cramming-in is causing failures.
There are two options:
- Replace the current nest of wires with a custom-made shield.
- Replace the entire thing with a standalone Arduino – one board that includes all the supporting circuitry
Either way, I think I should also move away from the two relays currently used to control the bang and the siren and just use transistors instead – I’m not sure why I didn’t do that the first time.
The schematic I have is not actually right as the indicator light has a voltage doubler to bring it closer to the required 24V. I should make a new one.
No data sheet for the central locking actuator and nothing much came up on googling. Attempted to measure peak curtent with multimeter that has no peak function… the highest value I saw was about 2.5A, so let’s assume 3A@11.1V. This probably requires a MOSFET to switch.
Siren is 350mA@12V according to the datasheet.
- How to use a transistor as a switch – useful guide to the required calculations
- How to use a mosfet as a switch – ditto, as the actuator (probably) requires more than a transistor can safely switch
- Making a custom shield
- Data sheet for the siren
- Schematic for powering an arduino using an LM7805
- Perfboard arduino, also, building an arduino on a breadboard
- Using an Arduino as an ISP, also includes a minimal circuit – no crystal
- Acrylic infra-red filters (data sheet)
- There are infra-red sensors but they are what is used in PIR detectors, they are expensive (£2.50 a go) and seem to require fairly complex supporting circuitry
- There are also infra-red receivers for remote controls. They are cheap and combine a sensor (perhaps a phototransistor?) with a pre-amp, and include daylight filtering. Possibly a good bet. Example (data sheet).
- Finally, bare phototransistors. Very cheap. From the datasheet it looks like they might allow more current to pass when exposed to more IR, which might be useful. Example (data sheet).
I tested a small solar panel by exposing it to IR, there was no difference at all in the voltage it produced. Though possibly other panels may work.