This is a poor man's geyser. It also saves electricity. The temperature is controlled by a microcontroller i.e., Digispark Attiny85.
Step 1: Parts Needed
- Plastic enclosure
- 12v 500ma step down transformer
- Relay board
- Digispark Attiny85
- Temperature sensor
- Mains cord
- 3pin Mains Socket
- 4.7k resistor
Step 2: Cutting the Enclosure
Cut and fit the switches and socket as shown in the pictures.
Step 3: Code
I took onewire temperature example and modified so that the heater turns OFF at 46 degrees and 44 degrees centigrade and beeps. Slide switch is used to change the temperature mode. It starts again if temperature drops.
Step 4: Assembly and Wiring
- Upload the sketch to the digispark.
- Solder 4.7k resistor between p0 and +5v pin in the digispark board.
- Now assemble and wire according to the pictures.
Note: Use same wire guage for the relay as heater's wire because it draws more power.