Hello,
You'll have to excuse me if this has already been covered at some stage I'm pretty new to the forum and certainly couldn't find anything similar. I've recently built a Wheatstone bridge circuit not dissimilar to the one shown below and its been working reasonably well.
The key differences are:
- I have a feedback resistor Rf from the output to the point D.
- I have two LEDs which act as signally LEDs; a green one parallel with the LDR and VR1 tells me my board is powered on and a red one at the output of the op-amp to tell me when the board has triggered to compliment the relay.
- The circuit was originally powered by 24V, a voltage regulator dropped the voltage down to 12V to power the rest of the circuit.
All is dandy with all that anyway, my problems occurred when I was told that the design needed to be powered by mains (not my choice, I liked the 24V option with a dedicated supply but heyho).
I achieved this using a transformer (a Myrra 45030) I've attached the datasheet but bottom line of it is it supplies 24V AC, a full bridge rectifier changes it to DC and a smoothing capacitor removes the ripple. Power on the circuit and
A) The red led comes on as well as the green which it isn't supposed to. The red is supposed to stay off until the board triggers.
B) When the light is introduced both LEDs switch off and the relay triggers.
Not sure what the problem is here. Am i not supplying enough current? Is something shorting my circuit somewhere along the line and I've screwed up my soldering?
Any advice would be greatly appreciated, I'd be happy to answer any questions as well provided they're not laced with insults and sarcasm of course.
Cheers!
You'll have to excuse me if this has already been covered at some stage I'm pretty new to the forum and certainly couldn't find anything similar. I've recently built a Wheatstone bridge circuit not dissimilar to the one shown below and its been working reasonably well.
The key differences are:
- I have a feedback resistor Rf from the output to the point D.
- I have two LEDs which act as signally LEDs; a green one parallel with the LDR and VR1 tells me my board is powered on and a red one at the output of the op-amp to tell me when the board has triggered to compliment the relay.
- The circuit was originally powered by 24V, a voltage regulator dropped the voltage down to 12V to power the rest of the circuit.
All is dandy with all that anyway, my problems occurred when I was told that the design needed to be powered by mains (not my choice, I liked the 24V option with a dedicated supply but heyho).
I achieved this using a transformer (a Myrra 45030) I've attached the datasheet but bottom line of it is it supplies 24V AC, a full bridge rectifier changes it to DC and a smoothing capacitor removes the ripple. Power on the circuit and
A) The red led comes on as well as the green which it isn't supposed to. The red is supposed to stay off until the board triggers.
B) When the light is introduced both LEDs switch off and the relay triggers.
Not sure what the problem is here. Am i not supplying enough current? Is something shorting my circuit somewhere along the line and I've screwed up my soldering?
Any advice would be greatly appreciated, I'd be happy to answer any questions as well provided they're not laced with insults and sarcasm of course.
Cheers!
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