Where Does the Rest of the Voltage Go in a Rectifier?

In summary, the conversation discusses taking voltmeter readings from a rectifier and the possibility of voltage loss in the form of voltage drop or due to current drawn by the load. It is suggested to check the AC voltages and use a filter cap to get accurate readings. It is also mentioned to not use an ohmmeter in a live power supply.
  • #1
sportynumair
10
0
When we take down voltmeter readings from the terminals of a Rectifier (rated 12V), we get the voltmeter reading as 4.5V. Does that mean the rest of the voltage is lost in the form of voltage drop? or is it because of the current drawn by the load? I would be glad if someone could please post the answer.

Thanks.
Numair
 
Engineering news on Phys.org
  • #2
If you measure the voltage on the other side of the rectifier, with the voltmeter set to AC, what voltage do you read?
 
  • #3
its coming out as 4.5Volts...so i want to know if the rest of the voltage is lost in voltage drop? or is it because of the current that the load on the secondary that is withdrawing. thanks
 
  • #4
Voltmeters put a very, very light load on the voltage being measured so no I don't think the voltmeter is loading the power supply. It's much more likely there's some other problem causing low voltage.
 
  • #5
If you don't have a filter cap, the output of the rectifiers is still AC( well, call it varying DC like you turn the negative half of the sine wave around and become like lumpy waveform), you are measuring the DC component of the rectified lumpy voltage. Put a 22 to 100 uF cap across the output and you should get the voltage.

If not, then read the AC voltages to make sure you have everything hooked up correctly.
 
  • #6
yungman said:
If you don't have a filter cap, the output of the rectifiers is still AC( well, call it varying DC like you turn the negative half of the sine wave around and become like lumpy waveform), you are measuring the DC component of the rectified lumpy voltage. Put a 22 to 100 uF cap across the output and you should get the voltage.

If not, then read the AC voltages to make sure you have everything hooked up correctly.

Thanks...but i want to know the loss in voltage is because of voltage drop? or is it because of the current drawn by the load?
 
  • #7
sportynumair said:
Thanks...but i want to know the loss in voltage is because of voltage drop? or is it because of the current drawn by the load?

Post a sketch of your circuit, with the AC and DC DVM readings you measured...
 
  • #8
sportynumair said:
Thanks...but i want to know the loss in voltage is because of voltage drop? or is it because of the current drawn by the load?

If you measure with just a multimeter, there is very little current drawn. If you don't have a filter cap, it is not accurate. To verify what I said, put your multimeter in AC Volt and measure, you should see AC voltage across the output of the rectifier. This is the AC I am talking about and this is the part that you miss when you measure with a DC Volt setting. As I said, without the filter, the output has a lot of ripple and it mess up your reading.
 
Last edited:
  • #9
If you measure with just a ohmmeter,

Do not make measurements in a live power supply with an ohmmeter - even a Fluke.
 
Last edited:
  • #10
Studiot said:
Do not make measurements in a live power supply with an ohmmeter - even a Fluke.

No, I should say multi meter, not a meter set in ohm! That would be bad! I changed the post already.
 

1. What is voltage reading?

Voltage reading is the measurement of electrical potential difference between two points in an electrical circuit. It is typically measured in volts (V) using a voltmeter.

2. Why is voltage reading important?

Voltage reading is important because it helps determine the health and performance of an electrical circuit. It can also be used to identify any potential issues or faults in the circuit.

3. What is voltage drop?

Voltage drop is the decrease in voltage that occurs when electricity flows through a resistor or load in an electrical circuit. It is measured in volts and can affect the performance of the circuit.

4. How is voltage drop calculated?

Voltage drop is calculated using Ohm's law, which states that voltage drop (V) is equal to current (I) multiplied by resistance (R). This can be expressed as V=IR.

5. How can I reduce voltage drop?

To reduce voltage drop, one can use thicker wires or cables with lower resistance, decrease the length of the circuit, or increase the voltage of the power source. Proper maintenance and regular checks can also help prevent excessive voltage drop.

Similar threads

  • Electrical Engineering
Replies
14
Views
2K
Replies
4
Views
1K
  • Electrical Engineering
Replies
4
Views
2K
Replies
8
Views
911
Replies
16
Views
1K
Replies
12
Views
1K
Replies
7
Views
1K
Replies
5
Views
2K
  • Electrical Engineering
Replies
12
Views
2K
  • Electromagnetism
Replies
10
Views
1K
Back
Top