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simulating a circuit - why no change

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MrDEB

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Have this schematic for a Hakko temp soldering iron and tried simulating using TINA but see no output change from 2a (between r14 and d1. Thinking this is what controls the on/off of the iron heater via the triac controller.
Am just simulating the three left side op amps seeing how u1c is the power supply.
perhaps LT spice would show correct simulation outputs. I have trouble w/ op amps in LT spice.
Even a description of this circuit operation.
I found that the sensor at room temp is 50 ohms. At the point of solder melt it is 180 ohms.
I have parts on order as well as a pcboard.
Here is the link to the schematic
 

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J2 is the negative supply, but you've connected it to the positive supply pins of the op amps. Likewise J1 is wrongly connected to the neg supply pins.
 
THANKS made changes but now V1 and V2 are 8.71v and 9v respectively?
Reguardless what the sensor resistance is.
Pretty sure the sensor is a temp resistor and not a thermocouple (applied heat but no voltage output.
I must be missing something?
 
V1 and V2 are simulated +12V and -12V supplies. The only way they can be other than those values is if (a) they have significant simulated internal resistance and (b) the circuit has something connected wrongly so that it is drawing excessive current. The type of sensor would not account for the values you have.
If the 9V is positive instead of negative there is a further problem.
Double-check the simulated circuit connections against the schematic (which is too fuzzy to read...re-post it as a gif or png image if you can).
 
That's clearer. Now, have you double-checked the connections as I suggested?
 
I doubled checked but will recheck. May have missed something. Won't be the first time.
 
You did miss something. Your sim has different connections from the circuit shown in post #6, particularly around the op-amp to which the sensor (R6) is connected. That would account for why you don't get the expected results.
I've done the sim in LTSpice, based on the circuit in post #6, using the circuit below. Note my zener D6 in the power supply is inverted compared to yours (correcting what I think is an error in the post #6 circuit). Note also the simulated power supply gives V+ = 13V, V- = -5V and Vref = +5V rather than the voltages you have used. My sim and the results are below. The curves are for 4 different values of the sensor resistance (50-200 ohms). I can post the .asc file if anyone asks.
 

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I'm aware my zener is 'upside down', as I mentioned above in post #9. That's intentional. If the zener is as shown in the link then it isn't acting as a zener at all; just as a normal forward-biassed diode which sets Vref at ~ 0.8V. Although that works, I doubt that's what the original designer intended, because the output voltage Vf1 (which is a measure of the sensor resistance) changes less with a small Vref than it does with a large Vref!
Attached is the .asc file. LTSpice doesn't include a model of the LM324, so the op-amps I simulated are LT1001.
 

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hi alec,
I thought we had sorted the LM324NS LTS model out the other day, do you still have a problem with it.??

EDIT:
Your circuit is fine with LM324NS
 

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Oops. Forgot about that! No probs with LM324NS Eric. Good of you to adjust the asc. Must be my bed-time...... :D
 
So I guess I should insert the ZD2 in as per the LTSPICE you posted?
I wonder if perhaps the designer used the ZD2 as in the schematic to ave something to do with the zero volt triac driver? don't see how??
will try out the asc file. THANKS
 
the 1n4006 has no definition?
1N4006 is not part of the standard LTSpice download, but was downloaded from the Yahoo user group. Use any other available diode for the sim (it's not critical for the present purpose).
Try the ZD either way round and see which you prefer.
 
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