What is the proper way to use a capacitor with a breadboard?

Other Hardware General Electronics
1

I have a Lidar Lite that needs a 680 uF capacitor to prevent inrush current from coming in, but I don't know exactly where to place it and since the sensor is expensive I would like to know for sure so that I do not mess anything up.

This is what the documentation tells me:

(Capacitor recommended to mitigate inrush current when device is enabled)
680uF capacitor (+) to Arduino 5v
680uF capacitor (-) to Arduino GND

Would I add the capacitor in the two red circles or do I have to do something with the two rows marked positive and negative that I circled in blue?

2

Where do the yellow and Orange jumpers go?

3

The yellow one is the 5v wire and the orange one is GND

4

Many of us normally use Red and Black for + 5 and ground. Makes it very obvious to everyone what the wires are for. Anyway, in your case attach the capacitor to where you put the orange circles, making sure you observe polarity on the capacitor. Probably would be better to move the wires over to the power rail and attach the capacitor over there, where it is plainly marked. That way you also have better access to the power rail for other things that will require power.

5

But I can tell you, it's not going to prevent inrush currents... Placed over the power rail it may help stabilize the voltage WHEN a inrush current happens but it does not prevent it.

Also, very exact value for something like that. How did you get that value?

6

I have a Lidar Lite that needs a 680 uF capacitor to prevent inrush current from coming in,

Not only will a capacitor not stop inrush current, it actually causes it on switch on.

7

Here are inrush current limiters
http://www.digikey.com/product-search/en/circuit-protection/inrush-current-limiters-icl/656273
and 2 tutorials

8

I would put it on the breadboard as close as possible to the power wires going out to the Lidar Lite. So if you have plugged it into the two long red/blue strips then put the capacitor on those strips. If you plugged it into some other strip on the board, then put the cap on those strips.

9

If this is the device, then hook up the capacitor as illustrated in the Operator's Manual:
LIDAR_Lite_v3_Operation_Manual_and_Technical_Specifications.pdf

10

Matt425x:
I have a Lidar Lite that needs a 680 uF capacitor to prevent inrush current from coming in.

You probably misunderstood whatever you were reading.

What happens is (and this is what I'm thinking only).... if your device (in this case the lidar) occasionally draws a lot of current (in addition to the usual amount it uses) in a SHORT AMOUNT of time (ie. in short high-level bursts every now and then), then that current (or power) will normally come directly from the power supply.

If you correctly assume some wire RESISTANCE between your power supply and your lidar's +ve power terminal, then a sudden (and momentary) burst of large current through the wire would mean a significant voltage DROP between your power supply and the lidar's +ve power terminal. That's due to the large current flowing through the model wire resistance. The result is ..... the voltage at the +ve power terminal could become significantly LOWER than the power supply's voltage due to the large current momentary burst. The lidar not only requires the required amount of current, but also the required amount of voltage (ie. required amount of power) to operate correctly. So it would be nice to have a way to prevent sudden and momentary drops in voltage at the +ve power terminal.

To acheive this, you can put a relatively large capacity capacitor very close to the +ve power terminal (of the lidar). The capacitor should be placed between the +ve power terminal and (say) ground. If it's a polarised capacitor (then polarity needs to be considered as well). Ideally this capacitor should have low series resistance. Its purpose is to live right next door (wall-to-wall) to the lidar, so that the capacitor can deliver the required burst of large current (over relatively SHORT period of time). If the capacitor only needs to deliver this required amount of current for a relatively short amount of time, then the voltage at the +ve power terminal can more or less be maintained (ie. it won't drop significantly). This is mainly because from circuit theory - the voltage across a capacitor cannot change instantaneously. So, for relatively short periods of time, the capacitor can at least maintain its terminal voltage and supply whatever amount of current is needed by the lidar.

11

So, for relatively short periods of time, the capacitor can at least maintain its terminal voltage and supply whatever amount of current is needed by the lidar.

agreed, but I don't understand why the capacitor is only needed in I2C mode, and not in PWM mode ......
maybe the I2C mode is more power hungry, or generates more bursts ?

12

alnath:
agreed, but I don't understand why the capacitor is only needed in I2C mode, and not in PWM mode ......
maybe the I2C mode is more power hungry, or generates more bursts ?

You got a good point there alnath. The garmin info doesn't explain everything clearly.

Eg. For the i2c details, at ....click here....it says:

  1. Write 0x04 to register 0x00.
  2. Read register 0x01. Repeat until bit 0 (LSB) goes low.
  3. Read two bytes from 0x8f (High byte 0x0f then low byte 0x10) to obtain the
    16-bit measured distance in centimeters.

For point 2, it says "Repeat until....". My question to them would be - repeat what?

13

Due_unto:
Where do the yellow and Orange jumpers go?

SIDE NOTE:

Sometimes I hate being colorblind. I see two brown jumpers, which are exactly the same shade of brown.

We are the reason that red and black are the standard wire colors for ground and the supplied positive voltage.

Or is it red and blue. All I'm seeing this evening is red and blue. &#@!

14

alnath:
agreed, but I don't understand why the capacitor is only needed in I2C mode, and not in PWM mode ......
maybe the I2C mode is more power hungry, or generates more bursts ?

I'd guess it's because I2C is more susceptible to noise.