# Questions tagged [voltage-divider]

A voltage divider is a circuit that produces an output voltage that is proportional to the input voltage. One typical configuration consists of a pair of resistors in series from the input voltage to ground, with the output voltage taken from the junction of the resistors. As an example two equal valued resistors will give an output voltage 50% of the input.

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### What wattage should the resistors or pots be in a car audio voltage divider?

My new radio amplifies the output too much and my car stock amplifier is non-adjustable. The only solution (that I know) besides putting the stock stereo back in, is 4 voltage dividers. I'd like to ...
40 views

### how to map 1V - 10V to 1.6V to 3.2V for voltage regulation using TL494

I am trying to design the given circuit where pin 1 is the non inverting terminal of comparator where I want to use a ref voltage of 1V - 10V but IC TL494 is accepting a voltage of 1.6V to 3.2V....and ...
132 views

I'm new to electronics. So basically I already understand Ohm's law and the math behind why this is the case. What I don't get is the idea behind it. Shouldn't the greater the load resistance be, the ...
391 views

### Why is the output voltage in my second op amp not the same as for the first op amp?

I saw this tutorial on a website. From that, I designed these circuits: In my circuits the voltage source is 12 volts. The tutorial says the output gain should be 2. In my second circuit the gain is ...
35 views

### Power Supply Module Internal Trimmer circuit / Remote Programming Resistor Value?

I am looking to incorporate a 45V supply into a design. These PFE1000-48V supplies have a trimming ability to get +/- 20%, based on +/- 20% variable resistor. I am trying to confirm what this resistor ...
654 views

### Term similar to "gain" for voltage dividers

In amplifiers, the magnitude of amplification is called "gain". Is there an equivalent for that on how much a voltage divider divides? Like how a voltage divider with a 100k and 39k resistor ...
148 views

### Is it normal that an analog voltmeter has about 7K ohm input impedance?

I have bought 10V 6c2 DC analog voltmeter, and I have tested it with a regulated DC power supply and it measured pretty accurately different voltages, however when I tried measuring the voltages in a ...
2k views

### How can you turn perceived brightness (log scale) into a linear analog output using an LDR?

This question is not about how to make illuminance (in lux) a linear function of voltage! It's about linearly representing the human perception of brightness, which itself scales logarithmic to the ...
497 views

### What is the difference between voltage regulators, resistors, and buck converters?

I am new to electronics and I would like to know the difference between voltage regulators, resistors and buck converters like the LM2596 and their advantages, disadvantages and use cases. I tried ...
85 views

### Voltage divider formula volt * kohm what equals?

I have query about when I have to solve the formula of the voltage divider. For example to solve the formula with respect to R1. My query is when I solve the formula at some point I have to multiply ...
1 vote
68 views

### How to accurately measure average temperature of a heating element?

Problem I'm trying to very accurately measure the heat of a nichrome wire as current is passed through it. My approach thus far has been to monitor current and voltage across the heating element and ...
84 views

### How do I calculate a voltage divider with an offset

I've got the following circuit: simulate this circuit – Schematic created using CircuitLab By running the simulation I can see that a signal voltage of 3.13 converts to an output of 2.14, but I'...
1 vote
202 views

### Voltage divider formula

How to find value for both R1 and R2 for Vout=1.23 volts, where Pot=5K, Vin=4.5 - 12 volts? simulate this circuit – Schematic created using CircuitLab In reality, I want to adjust lm2596 buck ...
81 views

### Why does voltage jump up with a rectifier circuit?

I've got a need to measure the integral of voltage with respect to time. I'm measuring a 25V AC power source through one of these voltage dividers to get it down to a workable 5I. I then rectify it ...
54 views

### Higher voltage from comparator to lower voltage at the output... how?

I am stuck on how to produce a lower voltage from an opamp used as a comparator that swings from +15V to -15V to +5V at the output, and 0V (when it swings to -15V) as well. I attached the circuit, but ...
140 views

### What are some ways to improve on a voltage divider without a voltage regulator IC?

We all know the basic voltage divider. It looks something like this. Two identical resistors and the voltage in the middle. I am, however, running into uses where this voltage divider is inadequately ...
199 views

### Reverse polarity protection without Zener diode

I find the following reverse polarity protection circuit everywhere online. Reverse polarity protection using PMOS and Zener diode: Can you replace the Zener and resistor with a voltage divider as in ...
116 views

### 36VDC to +/-15V linear regulator setup - will this design work?

I designed a +/-15V power supply setup and trying to find/fix problems before running another PCB production run. It will accept 36VDC (800mA) from an off the shelf part via a barrel connector. I ...
103 views

### Reducing 18-0-18 to 12-0-12V AC

My theory has run away so please bare with me if this is a dumb question. I have a transformer 18-0-18 feeding a BR to provide 40ish V to my DC power supply where I need +28V, +12V and +5V. All good ...
1 vote
105 views

### Why does my Push-Pull-Transistor blow up?

I'm currently working on a buffered voltage divider, followed by a Push-Pull stage to be able to source/sink up to 500mA per rail. The whole thing will is powered by 36VDC, then it's split by half ...
105 views

### Voltage limit of differential amplifier?

I need to measure the voltage difference between two high-voltage points (~500 Vdc). I'm thinking of using a differential amplifier with a gain of 1/100. While it behaves as I want it to in the ...
54 views

### Convert 24V battery output to 12V

I want to convert the output of my stronger Li battery (24V) to some devices that require 12V 24V Battery Specs: Output V: 21-29,4 V Capacity: 15 Ah Max Current peak: 36A Max Current: 18 A 12V Devices:...
78 views

### Inaccurate voltage divider

I'm creating a circuit which included a voltage divider. The divided voltage is connected to an ESP32 to read out the height of this voltage. Currently I get wrong readouts: after some examination the ...
58 views

### How can I measure a battery's level in percentages using a voltage divider and an ADC?

I want to measure the battery level of 4 AA (R6) batteries using a voltage divider made of 2 resistors which goes into the internal ADC of a PIC16F microcontroller with a 10-bit resolution. Knowing ...
38 views

### Power supply to an A4988 driver

I am starting to use the driver A4988, typically used for NEMA 17 motors and many others. As you may know, it has to separated VCC/GND pair of pins, one to supply the driver, the other for the motor ...
64 views

### Should I use a voltage regulator in tandem with a voltage divider to get 12V, 5V, and 3V from 14V power supply?

I am assembling a circuit that requires 12V, 5V, and 3V. I have a 14V power supply. To create the 12V, 5V, and 3V rails, should I use a 12V voltage regulator and then multiple voltage dividers to get ...
103 views

### Switched power supply output voltage modification

After days of research and experimentation, I was unsuccessful in modifying a power supply output voltage from 15.3V to 5V. My work was focused on the output section of this switched mode power supply,...
56 views

### How to calculate op amp output voltage

I have the following circuit: If I feed the circuit with 10 V all I get is about 8.2 V when VFD > 3.3 V. How is the resistor divider calculated (R94 and R95 + RV1) so I can get a voltage as close ...
29 views

### Auto-range test probe circuit

I've got a digital oscilloscope that can handle a maximum of 5V. On numerous occasions, if I know the range of a voltage, and it is above 5V, I have made simple voltage divider circuits to take ...
65 views

### High frequency voltage divider circuit, capacitor placement to lower ESL (is this a thing?)

I have a divider circuit similar to a x10 scope probe. I need a bandwidth of least 100MHz, preferably greater. I am using through-hole MICA capacitors (1%). The capacitors have a low enough ESL that ...
1 vote
153 views

### Reducing signal voltage with pull-down resistor

I have a signal that is really high compared to the inputs of a microcontroller and i have to step it down a bit.... Can I use a pull down resistor between the signal and the GND? Will this step down ...
51 views

### RTDs: Resistive Divider or Wheatstone bridge

I've inherited a PCB design in which the circuit for reading a 1k 2-wire RTD sensor is a simple resistive divider. The R_rtd is the pulldown part of the divider. The voltage of the divider is read ...
2k views

### How can a resistor have an effect on a circuit if it leads directly into the ground?

I'm new to electronics and I'm coming from a programmers perspective so sorry if this is obvious. ][1 This is a voltage division circuit (just a simple example from wikipedia.) R2 leads directly into ...
318 views

### Is this a correct way to divide and 'clamp' a noisy 10 V signal to 3.3 V?

I need to read a noisy 10 V Hall sensor square wave signal using an STM32 (3.3 V logic). To reduce the voltage I can use a simple resistor voltage divider, however, I'm not certain how to protect the ...
76 views

### How to increase load current for capacitive AC voltage regulator circuit?

I am studying fans and their working while visiting a factory, and I came across one problem that they're trying to solve. For an AC capacitive voltage regulator, how can we increase the amount of ...
120 views

### Zero current draw voltage divider equivalent

The problem: I am trying to read a DC analog voltage (from a battery) by an ADC on a microcontroller. This can be done by a voltage divider, but I am looking for a solution that has zero, or near ...
148 views

### Simple negative voltage divider circuit problem

My sensor gives output between -10V and +10V. Then I decided to use a simple voltage divider circuit to be compatible with the ADC input range. I used a power supply like the sensor, the expected ...
73 views

### Voltage divider dropping voltage more than expected

I'm trying to connect an ACS712 current sensor to an ESP32 ADC pin. The ESP32 expects 3.3 V, but the ACS712 can reach 4.5 V. When there's no current going through the ACS712, its signal is 2.5 V, so I ...
1 vote
98 views

### MCU GPIOs internal pull-ups with external voltage divider

I am designing a board based on STM32F7 with a dozen of Digital inputs that need to be 12V tolerant. On the first design, I was using a voltage divider to have the right logical high detection when ...
1 vote
60 views

### Determine the operating point of the circuit in the figure. Voltage divider, op amp, diode

simulate this circuit – Schematic created using CircuitLab Since the operating point of the circuit is determined by analysing it in DC, the capacitors behave as open circuits. At this point, as ...
44 views

### How do I determine what range (not necessarily value) of resistors to use for voltage dividing [duplicate]

I'm getting back into electronics as a hobby and doing some refreshers having been away from it for a long time. I understand Ohm's law and voltage dividing, however, I'm not sure I understand what ...
84 views

### How does this offset and gain amplifier work

The circuit below is meant to scale and offset Vin to Vout: In the actual application Vin is a battery voltage (4 to 5.5V ish) and Vref is a fixed regulated voltage derived from it (3.3V). The op-...
86 views

### voltage divider inside differential op amp configuration

I'm working on a DIY analog synth based on the CEM3340 chip. When feeding it 12V at VCC it will output waves at different amplitudes that I'll want to scale to 5V to -5V: Square: 0-10.7V Sawtooth: 0-...
71 views

### Why can't I use a 12 V DC power supply, voltage divided to get a 9 V drop across a resistor, to power a 9 V DC motor? [duplicate]

I have a 12 V DC power supply and a 9 V DC motor available to me. I want to use the 12 V power supply to power the 9 V motor, and I expected I could do this with voltage division. I built this circuit,...
325 views

### Choosing register value for NTC with voltage divider

I need some help to choose resistor for voltage divider circuit to read temperature using NTC Thermistor. I'm planning to use STM32 with his 12bit ADC. The NTC I'm using has the following properties: ...
117 views

### Energizing a relay with a lower coil voltage than my power supply

I'm using a 72 VDC power supply to drive some equipment. I need to drop that voltage down to 48 VDC to drive a relay I'm using. What are my options to energize the relay coil and what specs do I use ...
1 vote
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### Does this circuit look correct to connect DA-15 (Gameport/MIDI) to RPi (MT32Pi)?

I'm trying to connect an older PC with a DA-15 (Gameport/MIDI) to a Raspberry Pi using MT32Pi. The Gameport/MIDI is +5v and the RPi is +3.3v so I'm using an optocoupler and voltage divider. Does this ...
114 views

### Choosing resistor values for op amp termination

I need to terminate an unused op amp and plan to use the recommended circuit below with +3.3V. How do I choose the resistor values? The op amp I'm using is the MCP6002 (datasheet). I understand too ...
1 vote