I had been thinking about this project for a while and got really inspired by Hans Forsberg's efforts and results. I wanted to make a very simple version of what he's been doing. I also wanted it to be small, cheap, using common analog components and discarded items.
I wanted to avoid programming and 3D printing - not that I don't love that stuff, but to keep this mechanically and electrically simple, cheap and accessible. I might make a microcontroller-based model later, but I like to work with analog for simple projects like this as it tends to limit the irrisistable scope creep that constantly tempts me to add more features.
I hope this can be the type of project you can build quickly and easily, experiment, try it out and improve on it over time. There is a lot of room and possibilities for improvement and enhancement. Solar charging, computer vision, do it all with a single microcontroller, print better parts, more efficient design, better power management... lots of room for improvement :)
I've already built a prototype and started testing it with birds that visit my balcony (mostly pigeons, but some jackdaws, crows and magpies). The vibration motor does not startle them - especially when they learn it means a peanut is coming,
The circuit is fairly straightforward:
- PIR sensor (the one thing I could not find laying around and had to buy. This turns on the rest of the circuit when triggered.
- 555 monostable vibrator to keep the circuit on for ~30 secs after the PIR is triggered. There is a diode leading from pin 6/7 to the trigger. This allows the PIR to reset the timer during a cycle, keeping the thing continuously on while a bird is in front of the PIR.
- LM358 dual op amp for the IR proximity sensors made from IR leds and phototransistors
- another 555 for a monostable vibrator - when the drop sensor sees something it turns the vibration motor on, when the dispense sensor sees something it turns it back off. If the dispense sensor doesn't see a peanut within 24 seconds it turns the dispenser off.
- a third 555 astable vibrator - to use as an optional timed dispense to get birds used to it as a food source
- small DC motor (the one I used is marked 2 volts) with a slice of cork pressed on the axle and some screws in one side of the cork to make it vibrate
- some resistors, capacitors, a few transistors and diodes and signal LEDs to indicate what's going on
The circuit was the simple part.
Biggest problem I had to solve was dispensing one (or maybe two) peanuts at a time reliably without a complex mechanism or making peanut butter. A vibration feeder made from two jar lids with offset holes finally did the trick. This was a challenging puzzle to solve. I probably spent most of the project time on this.
One interesting thing I discovered was that black shrink tubing, or anything matte and colored black with carbon, does not trigger the IR proximity sensors, making it a great material to use inside the enclosure around the sensors. It lets you turn up the sensitivity a bit without worrying about getting triggered by the enclosure itself - great for monitoring openings and chutes for passing objects.
Circuit
Disabled
The sensors and their op-amps are off until the PIR is triggered.
If it's in timer mode, the TIMER (astable vibrator) is also on.
Enabled
- PIR sensor triggers monostable vibrator
- Sensor On/Off Monostable vibrator turns on rest of circuit via an NPN transistor and keeps it on for ~30 sec after the last PIR trigger
Deposit
- Deposit sensor detects passing object and triggers op amp 1
- Op amp 1 triggers Motor Monostable vibrator to go high
- Monostable vibrator turns on vibration motor via an NPN transistor
Dispense
- Dispense sensor detects a passing peanut and triggers op amp 2
- Op amp 2 triggers bistable vibrator to go low
- Monostable vibrator turns off vibration motor via an NPN transistor, or the motor will turn off by itself after 24 seconds (a bit long, and I will shorten it after some...
This project is way cool. Do you have a video of a bird dispensing an item and receiving a peanut?