i am making a fully analog bms , using the following components,
ICs (Must be DIP / Through-Hole type)*

* 1x LM358 (Dual Op-Amp)
* 1x uA741 (Single Op-Amp)
* 1x NE555 (Timer IC)

*Sensors & Controls (For Breadboard)*

* 4x 10k Potentiometers (Small "Trim Pot" or "Preset" type works best for breadboard)
* 1x 10k NTC Thermistor (Temperature Sensor)

*Transistors & Diodes*

* 5x BC547 NPN Transistors
* 10x 1N4007 Diodes

*Outputs*

* 1x 12V Relay (5-pin "Sugar Cube" type)
* 1x 12V DC Fan (Small size)
* 5x Red LEDs
* 5x Green LEDs
* 1x Small 12V Bulb (or DC Motor) for load

*Resistors (1/4 Watt)*

* 20x 1k Ohm
* 10x 10k Ohm
* 5x 22k Ohm
* 10x 220 Ohm (or 330 Ohm)

*Capacitors*

* 2x 10uF Electrolytic Capacitor (16V or higher)

*General / Power*

* 1x Breadboard (Standard size)
* 1x Bundle of Single Strand Wires (or Jumper Wires Male-to-Male)
* 1x 12V DC Adapter (1 Amp) + DC Jack connector (Female)



so i am doing this simulation and i am not getting the results i need , like i think connection errors but i can, figure them out.
the project idea is simple , it takes 2 inputs temp and voltage, compares it against a threshold.
working principle
Stage 1 — Voltage monitoring (LM358 dual op-amp)
The LM358 (U1) is used as two independent voltage comparators. U1:A compares the battery voltage (set via potentiometer RV1) against a 4.2V reference (REF_4.2, set by another trim pot). If battery voltage exceeds 4.2V (overvoltage), the output goes HIGH. U1:B does the same for the undervoltage threshold of 3.3V (REF_3.3) — if the battery drops below this, its output goes HIGH. Diodes D1 and D2 on the outputs act as an OR gate — either fault condition triggers the relay driver transistor Q2 (BC547), which pulls in relay RL2 to disconnect the load. D3 is a freewheeling/flyback diode across the relay coil to suppress the voltage spike when the relay de-energises.
Stage 2 — Temperature monitoring (uA741 + NE555)
The NTC thermistor forms a voltage divider with a fixed resistor. As temperature rises, the thermistor resistance drops, pulling the voltage at the uA741's (U2) inverting input higher. When this crosses the TEMP_REF threshold, the 741 output goes HIGH, which triggers the NE555 (U3) in monostable mode. The NE555 output then drives transistor Q1 (BC547), which switches on the 12V DC fan and lights the red LED alarm.
Stage 3 — Output stage
All outputs are transistor-driven (BC547 is an NPN — a HIGH signal at its base turns it ON). The relay switches the main load (bulb/motor). The fan cools the battery. LEDs give visual status.

 

Welcome to AAC!

The LM358 (U1) is used as two independent voltage comparators.

Why are you using an opamp as a comparator? LM393 would be better.

so i am doing this simulation and i am not getting the results i need , like i think connection errors but i can, figure them out.

What are the supplies for the uA741?

Your schematic is essentially unreadable due to the unnecessary wire jogs, unnecessary wire crossings, misplaced connection dots, and poor flow.

What is the purpose of RL2? It switches ground to L1, but the other terminal of L1 is also connected to ground.

*Transistors & Diodes*

* 5x BC547 NPN Transistors
* 10x 1N4007 Diodes

The schematic shows 2 transistors and 4 diodes being used. Why are you using 1N4007?

 

As noted, your schematic is a lazy-drawn mishmash and very difficult to read.
So please redraw it to address these issues if you want us to understand it.

Look at well-drawn schematics if you need to know how its done.
They have a minimum of dot connections, wire jogs, and crossed wires. while yours has an abundance of those.

I do see that D1 and D2 are back-to-back (although not immediately obvious the way it's drawn) so they do nothing.

 

Q2 is also connected wrong.

When you repost the schematic, turn of that horrible grid.

 

As noted, your schematic is a lazy-drawn mishmash and very difficult to read.
So please redraw it to address these issues if you want us to understand it.

Look at well-drawn schematics if you need to know how its done.
They have a minimum of dot connections, wire jogs, and crossed wires. while yours has an abundance of those.

I do see that D1 and D2 are back-to-back (although not immediately obvious the way it's drawn) so they do nothing.

i took multiple days to do this fr. I am a beginner, this like my first time using proteus and also first time creating a fully analog circuit , so i am not very good at it. I can't figure out how to do it, i have been doing it for days now i still can't figure out.

 

What is the purpose of RL2?

well the purpose of rl2 is it to safely cut off the battery if the voltage is not in desired range.but i think that part in this circuit has some major connection errors so i had to make it separately , now that works. ig the relay part was the easiest so i could figure that out but the voltage sensing area is driving me nuts, like can you recommend somewhere i can refer to understand making comparator circuit

 

Why are you using an opamp as a comparator

syllabus restrictions, this is a assignment kinda project , even lm358 is not in the project criteria

 

Q2 is also connected wrong.

When you repost the schematic, turn of that horrible grid.

i will

 

can you help me figure out whats wrong with this .

 

hi ja,
What is the circuit intended to do?
It appears the OPA is upside down.
E

 

hi ja,
This is what LTSpice shows when your OPA inputs are corrected.

I have used a vin sweep voltage to replace the 10k Pot.
E

 

syllabus restrictions, this is a assignment kinda project , even lm358 is not in the project criteria

If this is schoolwork it needs to be in the Homework Help forum and member responses will be restricted to guidance.

 

View attachment 364998
can you help me figure out whats wrong with this .View attachment 364999

Spice simulation requires a ground connection. You have no ground connection in the circuit.

 

can you help me figure out whats wrong with this .

Some simulators require a ground connection before they'll work. Seems silly, but it is what it is...

Still too many unnecessary wire jogs.

 

Some simulators require a ground connection before they'll work. Seems silly, but it is what it is...

Still too many unnecessary wire jogs.
View attachment 365026

ooo thanks now i am like making a window comparator for this like i want to make the voltage to be between 2 particular values. i need this proteus tip fr.Thank you.

 

hi ja,
What is the circuit intended to do?
It appears the OPA is upside down.
E

it's for voltage regulation of a battery. if voltage is not the desired value the led has to light up.
thank you

 

i made the window comparator thank you it works perfectly.

 

btw what is wire jogs

 

i am trying add the relay circuit to it. like the relay should cut off the load when battery voltage is not desired.but the motor always rotates.

 

I feel one end of the coil side to be grounded.