Hi,
I work at a plant nursery where we have some very young plants germinating on heated beds. They are really simple - just 240v in, thermostat, 240v out plus a temperature probe. The trouble is, they are so simple they don't even have a light to tell when they are on or off. We recently had one running off of a dodgy extension lead and we found out one morning that it had tripped the circuit breaker in the fusebox and they had all been off all night.
What I need is to add a light to the control box which tells when it's on or off but I need to be able to tell if the heating element is making a circuit or if there are any breaks in the wire. Hence, I can't just put a 240v neon indicator in parallel with the thermostat controlled output because I still won't know if there's any current going through the element.
I have looked around on the internet and found a very simple circuit using only 3 diodes, 1 resistor and an LED but I am not sure if this is too simple or if it really will work with only these components.
Basically, there are 2 diodes in series with the heating element, then another diode, the LED and a resistor in parallel with these 2 diodes but pointing the other way. I hope that makes sense, I don't have time to draw and upload a diagram right now but I will try later.
What I eventually want is to have a board with 4 or 5 of these current detecting circuits and then have these connected to 4 or 5 regular 240v mains sockets so whatever I plug into them (ie the heated beds) I can tell whether it's working or not.
Thanks a lot, this will really save us some worrying each night as our whole business depends on these plants growing properly.
Cheers,
John.
I work at a plant nursery where we have some very young plants germinating on heated beds. They are really simple - just 240v in, thermostat, 240v out plus a temperature probe. The trouble is, they are so simple they don't even have a light to tell when they are on or off. We recently had one running off of a dodgy extension lead and we found out one morning that it had tripped the circuit breaker in the fusebox and they had all been off all night.
What I need is to add a light to the control box which tells when it's on or off but I need to be able to tell if the heating element is making a circuit or if there are any breaks in the wire. Hence, I can't just put a 240v neon indicator in parallel with the thermostat controlled output because I still won't know if there's any current going through the element.
I have looked around on the internet and found a very simple circuit using only 3 diodes, 1 resistor and an LED but I am not sure if this is too simple or if it really will work with only these components.
Basically, there are 2 diodes in series with the heating element, then another diode, the LED and a resistor in parallel with these 2 diodes but pointing the other way. I hope that makes sense, I don't have time to draw and upload a diagram right now but I will try later.
What I eventually want is to have a board with 4 or 5 of these current detecting circuits and then have these connected to 4 or 5 regular 240v mains sockets so whatever I plug into them (ie the heated beds) I can tell whether it's working or not.
Thanks a lot, this will really save us some worrying each night as our whole business depends on these plants growing properly.
Cheers,
John.