Hello all,
The attached pdf file shows the circuitry i used.
(Please keep in mind i am still sort of new to transistors)
Goal:
The goal of the project is to create a voltage regulator that can regulate 9V and at the same time, disconnect a load from the circuit at conditions of 40 degrees celcius and 1A.
Basic Operation:
The regulator would be designed such that it outputs a constant 9V which would be the voltage drop across the load. It is desired that the load be separated from the circuit for temperatures greater than 40 degrees celcius and current exceeding 1A. Therefore, sensing circuits are implemented such that it would detect these parameters and control the load accordingly. The load is controlled by a switching circuit, comprising of MOSFETs. The MOSFETs are arranged such that it produces an AND gate (Tmf1 and Tmf2) and receives signals from the temperature and current sensing circuit so it would behave accordingly when the conditions are not met. This means that a current would only allow a current to flow through the load when the temperatures is less than 40 degrees celcius and current is less than 1A. The alternative path for the current to flow is a short circuit to ground (probably a poor decision but i was limited to time), so that when the 1A flows, the load would not be going on and off repeatedly very quickly.
Problem:
There are multiple problems however these are the main ones.
-The problem i am having with my circuit is that when the current passes the 1A, the current is sent into the alternative path with the mosfet Tmf4 which is fine but the load keeps going on and off repeatedly irregardless (even though i took it into consideration) and also making a sort of high pitch sound. I know the load is on and off repeatedly because there is a small glow in the LED.
-When currents greater than 1A flows, the voltage across the Zener diode changes greatly which messes up the regulated output which causes a problem because my references (potentiometers) are set using it.
- The current limiting circuit also messes up the regulated voltage a bit but i guess it is because the MOSFET is not ideal and draws little current from the base even when it is off.
-Even my LM35 temperature transducer is affected by the high currents. It gives very wrong output values at the higher currents.
-------------------
Please ask questions about my design for any clarification or other purposes. I am open to any such criticism. I have considered letting the load disconnect at 1A and coming back on at around say 0.95A. In addition to that, i am considering how to keep the current through my zener constant. I more than likely have more problems but these are my main ones.
~Thanks , all responses are much appreciated
The attached pdf file shows the circuitry i used.
(Please keep in mind i am still sort of new to transistors)
Goal:
The goal of the project is to create a voltage regulator that can regulate 9V and at the same time, disconnect a load from the circuit at conditions of 40 degrees celcius and 1A.
Basic Operation:
The regulator would be designed such that it outputs a constant 9V which would be the voltage drop across the load. It is desired that the load be separated from the circuit for temperatures greater than 40 degrees celcius and current exceeding 1A. Therefore, sensing circuits are implemented such that it would detect these parameters and control the load accordingly. The load is controlled by a switching circuit, comprising of MOSFETs. The MOSFETs are arranged such that it produces an AND gate (Tmf1 and Tmf2) and receives signals from the temperature and current sensing circuit so it would behave accordingly when the conditions are not met. This means that a current would only allow a current to flow through the load when the temperatures is less than 40 degrees celcius and current is less than 1A. The alternative path for the current to flow is a short circuit to ground (probably a poor decision but i was limited to time), so that when the 1A flows, the load would not be going on and off repeatedly very quickly.
Problem:
There are multiple problems however these are the main ones.
-The problem i am having with my circuit is that when the current passes the 1A, the current is sent into the alternative path with the mosfet Tmf4 which is fine but the load keeps going on and off repeatedly irregardless (even though i took it into consideration) and also making a sort of high pitch sound. I know the load is on and off repeatedly because there is a small glow in the LED.
-When currents greater than 1A flows, the voltage across the Zener diode changes greatly which messes up the regulated output which causes a problem because my references (potentiometers) are set using it.
- The current limiting circuit also messes up the regulated voltage a bit but i guess it is because the MOSFET is not ideal and draws little current from the base even when it is off.
-Even my LM35 temperature transducer is affected by the high currents. It gives very wrong output values at the higher currents.
-------------------
Please ask questions about my design for any clarification or other purposes. I am open to any such criticism. I have considered letting the load disconnect at 1A and coming back on at around say 0.95A. In addition to that, i am considering how to keep the current through my zener constant. I more than likely have more problems but these are my main ones.
~Thanks , all responses are much appreciated
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