Water sensor/pump switch

[McSpuds]

I have a radio controlled ship that has a bilge pump that uses a 6vt motor. The motor has a automatic switch that turns on the motor when the water gets to a certain level.

Here is a pic of the homemade device:


**broken link removed**

**broken link removed**

I have broke down the resin molding and there is actually two electronic pieces that make this work. A Rayex L90-5W Relay and a TIP120 Semiconductor. The process of removing the resin also made the wiring impossible to read what was connected to what.

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_134949_-1

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_1095849_-1

The 5 leads are as follows:

Top red and black leads go to the 6vlt motor
Deans plug with red and black leads go to the power source, 6vt gel cell
Green lead is placed at bottom of sump
The Blue lead is soldered onto a brass tube. This tube is set to the water level you wish the motor to turn on at.

\Very simple set up except I am no electronics person and need help with the wiring diagram. The water reaches the brass tube and the switch turns on the motor.

Can somebody please tell me what needs to be wired to what?

 

[Brevor]

Can somebody please tell me what needs to be wired to what?

Im not sure what you mean ? as you have already stated

Top red and black leads go to the 6vlt motor
Deans plug with red and black leads go to the power source, 6vt gel cell
Green lead is placed at bottom of sump
The Blue lead is soldered onto a brass tube. This tube is set to the water level you wish the motor to turn on at.

 

[McSpuds]

I am not sure how the TIP120 is wired to the L90 Relay. I see where the wires go to, just not where they come from... Did that clear it any?

In that pic, you can see the relay and the leads going off of it. The TIP120 is inside of the grey resin you see behind the relay. In the process of removing the resin to see how the relay is wired, we found the TIP120 in behind it. And we can not see what wires came from where...

 

[Brevor]

Oh I see what you mean, Your trying to copy the internal circuit. It's hard to tell from a photo but most likely it's just a common emitter relay driver. Unfortunatly I dont have software that I can post a schematic here. Perhaps someone else can. Basically the +12 Volts connects to one side of the relay coil and the collector of the TIP 120 connects to the other end of the coil. The emitter is grounded. The base connects to one of the probe wires and the other probe wire connects to + 12 Volts possibly through a resistor. There should also be a reverse biased diode (1N4001) across the relay coil.

 

[Brevor]

Here is an example look at the circuit with the relay.

http://www.kpsec.freeuk.com/trancirc.htm

 

[mbarazeen]

its a darlington transistor that is having high gain, as i beleive its simply connected to relay. and the green wire goes to +ve and the blue wire goes to the base of the transsistor via a resistor. 47 ohms?? (for 120mA) to base. if water level comes bellow the blue wired rod then it will stop.