low coolant alarm

First mock up

Aaaaah it's like the 3 month ultrasound scan, the T-Bar lca is on the way :woohoo:

... looks like it will be within my budget finaly ?
Count me in 4one :yesnod:

Psymon wrote: Anybody be interested if i were to knock some of these up?

Put me down for one please.

Psymon wrote: First mock up

Simon ~ any idea on price yet?? Andy Capy who makes the LO-Larm system has written an article in this months Enjoying MG, the MGOC monthly mag. He sells his kit for £65 inc p&p. this uses the existing bottle (lots of problems with his first version. loss of pressure and false readings~ second version better but i have read that it is very difficult to get the external sensor to stick to the bottom of the bottle and to stay stuck!!)

Less than that, price will be mainly dependent on the senor. i'm targeting between £25 to £35.

Toying with the idea of using a capacitive sensor from VW, they are less than a fiver. got one order as by the looks of it i'll need to find a nut of somesort to mount it, looking around for the same sort thing but with the thread comming out the bottle instead like the broken finger sensor.

Psymon wrote: Less than that, price will be mainly dependent on the senor. i'm targeting between £25 to £35.

Toying with the idea of using a capacitive sensor from VW, they are less than a fiver. got one order as by the looks of it i'll need to find a nut of somesort to mount it, looking around for the same sort thing but with the thread comming out the bottle instead like the broken finger sensor.

Put me down for one Simon.....

Found a bonus of using a capacitive sensor, the circuit has to be tunned to the conductivtly of the coolant. If coolant mixture is wrong (ie to strong or to weak) its conductivity will be different, which could tigger the alarm as well. suppose oil leaking into the water system would also have the same effect. With enough sensitivity HGF could be detected earlier than the coolant disapearing.

Currently redesigning my circuit to suit a capacitive sensor instead of a switched sensor. Main reason being is to drive the sensor with an AC current instead of the DC supplyed by the car, This will reduce any electrolysis occuring in the coolant increasing the life of the sensor. Using stainless steel sensor tips will stop any further reaction from electrolysis from coating the sensor.

Psymon wrote: Found a bonus of using a capacitive sensor, the circuit has to be tunned to the conductivtly of the coolant. If coolant mixture is wrong (ie to strong or to weak) its conductivity will be different, which could tigger the alarm as well. suppose oil leaking into the water system would also have the same effect. With enough sensitivity HGF could be detected earlier than the coolant disapearing.

Currently redesigning my circuit to suit a capacitive sensor instead of a switched sensor. Main reason being is to drive the sensor with an AC current instead of the DC supplyed by the car, This will reduce any electrolysis occuring in the coolant increasing the life of the sensor. Using stainless steel sensor tips will stop any further reaction from electrolysis from coating the sensor.

That sounds really good - like the idea of the dilute coolant triggering an alarm, i am sure that loads of people just add tap water to the bottle. i assume that it is your intention to drill a hole in the bottle to fit the sensor ?? may be a bit fiddly getting a nut on the sensor though through the tank neck! ~ the thread on the sensor will be metric as its VW, if you could give me the VW part number i will get one too and try to match the threads, a stainless steel half nut will be ideal, i know a couple of companies that could supply these and you can buy just one nut or bolt from them.

Will do. My backup plan however is two stainless steel rods/bars/screws or something poking down from the top of the bottle avoiding having to making any holes at coolant level. this is certainly the method i'll use for the my prototype.

Currenty waiting for all my components to turn up so i can build a test curcuit.

Psymon wrote: Will do. My backup plan however is two stainless steel rods/bars/screws or something poking down from the top of the bottle avoiding having to making any holes at coolant level. this is certainly the method i'll use for the my prototype.

Currenty waiting for all my components to turn up so i can build a test curcuit.

Any progress report ? - more of a bump really

Got all the bits now, will be putting together a prototype during the week