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    Current monitor/sensor

    Hello again, i have had problem with RC filter from PWM but i solve it with proper resistor and capacitor value and i get DC signal into positive pin of OP, see picture below. When i put 100 bit value i get around 0,5V which is OK. There is one onother problem which i have still not solve...
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    Current monitor/sensor

    It's maybe batter to add 100E restor from 24V supply to BD139 collector and onother 100E resistor between emmiter and output transistor bases? Or there should be additional relay to provide open circuit while battery is disconnected and no current flow when battery isnt present at all?
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    Current monitor/sensor

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    Current monitor/sensor

    This is exactly the main problem in circuit, if battery not connected and positive voltage apply in + iput of OP by chance, so this mean that high current try to flow through BD139 and 220E resistor and buri it. Circuit is for battery test purpose, programmable cotrol discharger to test battery...
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    Current monitor/sensor

    When i have 0V on + input pin of opamp LM324 then i have 24V on ouput and bd139 is turn on end also when i put resistor 220W between BD139 emmiter and ouput transistor bases. This is all againts how i want to circuit works, maybe something wrong with opamp? Is there any chance to no current...
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    Current monitor/sensor

    Yes, thats thrue, but when i put resistor between BD139 emmiter and two output transistor bases this mean that if no zero voltage on power resistor (beacause of some unfourable reasons) current flows through output transitor in any case also without battery because there is forward biased. I...
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    Current monitor/sensor

    Have you any idea how to avoid this effect? It could be ideal that no current flow through output transistor when battery is not connected onto circuit and 0V is on discharge power resistor via OP feedback.
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    Current monitor/sensor

    Thanks! I tried this and works fine, i put the 680E resistor between emmiter and bases, but there is one think, it can't possible to make no current flow throught circuit if battery disconnected, some current always flow into transistors, around 1.5ma regarding my simulation.
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    Current monitor/sensor

    Transistor is burned out again so i just wondering that the main problem is that at power supply present and before output of MCU provide zero voltage to + input of OP very high current through BD139 and in bases of output transistor because battery not connected at start. As is said i have no...
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    Current monitor/sensor

    So, this is circuit i want to make controled battery discharge with and as i said don't work as i expected. When i connect power supply unlimitet current want to flow through circuit bit i don't know why?  Maybe you are confused with my comment about power supply, no, i just use power supply...
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    Current monitor/sensor

    I tried to replace OP and BD139 and there is the same story, when i connect base on BD139 then try to flow unlimitec current from power supply, i have not connected battery at all. I also chech the output transistor and seems ok. Its logical that current want to flow through output transistor...
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    Current monitor/sensor

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    Current monitor/sensor

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    Current monitor/sensor

    I was also wondering this because before when I used PNP output transistor in common emmiter orientation if you remember circuit all works fine, the main probmel was as you said ringing because voltage gain.
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    Current monitor/sensor

    Yes, but if I put 0V on + input pin of OP, on - pin should be 0V or not? So on power resistor 0,5E should be 0V and no current should flow through battery, why in my case flow around 1A through BD139 when I connect power supply on circuit so 24V??
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    Current monitor/sensor

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    Current monitor/sensor

    Yes, thanks for all your help, I just was afraid that discharging doesn't work in that kind of circuit orientation but such design work correctly for now, I mean you proposal NPN follower.
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    Current monitor/sensor

    So, what is difference between charger and discharger, my idea was in switching relays which reconnect lines and provide both orientation?? What do you think about that?
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    Current monitor/sensor

    sorry but I will very grateful if you give me advice about discharge circuit, I know that my version will wok but probably you have some critical comment, you have more experience!
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    Current monitor/sensor

    I want to use circuit above but instead of supply on power transistor there is battery which discharges, for charge it we use power supply voltage, so different orientation of circuit. Is there any calculation for additional RC pole, in my current circuit remains some ripple with one single rc...
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