Solenoid Indicator Light
My soldering skills have been on the decline and instead of moving my DIY controller from the breadboard again to the circuit board I decided to get a Milwaukee pH controller. I don't want to mess with the circuit board again. Since the Milwaukee isa lovely yellow-green and the solenoid light blinks when it's on, I decided to move it inside the cabinet. I like being able to see the solenoid on at a glance, however, and decided to add an indicator light. The circuit is very simple and consists of:
a small plastic box (an old asprin bottle would do) to house the components.
one foot of speaker wire
0.47 uF non-polarized capacitor, >200V
56K ohm 1/4 watt resistor
Plastic diode mount pressed in a hole drilled in the cabinet.
The diode is needed because I'm lighting the LED with AC current from the plug on the solenoid; one end connected to the capacitor and the other to the resistor The capacitor and resistor drops the voltage to about 10 volts and the circuit runs cool with sufficient brightness from the diode.
Schematically, the LED and the diode are joined in parallel, anodes to cathodes. At the LED anode junction one end of the capacitor is attached. The resistor is attached at the LED cathode junction. The free ends are connected in parallel with the solenoid. In practice, the speaker wire is used to connect the LED to the diode and the capacitor and resistor leads to the solenoid.
Andrew, MASI Treasurer
This message is always under construction: 75-gallon tank; 2, Eheim 2026 filters - one twice broken; Tek Light with 4, 54W T5s (6000K) ; Sand on top of 4:1 sand:clay mixture; Milwaukee CO2 controller; PlantGuild vortex CO2 reactor; pH = 6.6, kH=70mg/l, GH=120mg/l; EI; Flourish excel on 50% weekly water change: AGA Member.