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Updated How to Connect a Circuit to Labrador (markdown)

Chris Esposito 2018-02-06 14:35:40 +11:00
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How-to-Connect-a-Circuit-to-Labrador.md

@ -28,10 +28,18 @@ I tested this theory in real life by building the voltage divider and connecting
You can do the same. If you’ve not dealt with oscilloscopes or signal generators before, it’s the best place to start. You can do the same. If you’ve not dealt with oscilloscopes or signal generators before, it’s the best place to start.
![image_3](https://user-images.githubusercontent.com/22040436/35839086-9b8ae602-0b42-11e8-8111-a5a5922af8d8.jpg) ![image_3](https://user-images.githubusercontent.com/22040436/35839086-9b8ae602-0b42-11e8-8111-a5a5922af8d8.jpg)
Above is a picture of my breadboard.
`(NOTE: If you’re not familiar with how the connections in a breadboard work, I recommend checking out Adafruit’s tutorial. I also recommend tearing the backing off of a breadboard at least once in your life. Just make sure you have duct tape handy to put it back together again.)` `(NOTE: If you’re not familiar with how the connections in a breadboard work, I recommend checking out Adafruit’s tutorial. I also recommend tearing the backing off of a breadboard at least once in your life. Just make sure you have duct tape handy to put it back together again.)`
Above is a picture of my breadboard. The oscilloscope CH2 pin is connected directly to Vin with a standard solid-core jumper wire. The oscilloscope CH1 pin is connected to Vout. The GND node of the voltage divider is connected to the GND pin of the Labrador. Vin is connected to the signal generator CH1 DC output. The resistors used were both 6.8k, meaning that the voltage at Vout should be approximately half (NOTE: I say "approximately half" because no component is 100% accurate. The resistors I used have a tolerance of +/- 1%, meaning that the actual resistance could be anywhere between 6.73k and 6.87k.) the voltage at Vin. You can do the maths if you don’t believe me. The top yellow wire connects Vin to both the signal generator CH1 as well as the oscilloscope CH2 pin.
The lower yellow wire connects Vout to oscilloscope CH1.
The black wire connects the circuit's GND pin to Labrador's GND pin.
The resistors used were both 6.8k, meaning that the voltage at Vout should be approximately half the voltage at Vin.
`(NOTE: I say "approximately half" because analog components aren't 100% accurate. The resistors I used have a tolerance of +/- 1%, meaning that the actual resistance could be anywhere between 6.73k and 6.87k. This can lead to slight imbalances in your circuits. If only there are a $29 tool that could measure such things...)`
![image_4](https://user-images.githubusercontent.com/22040436/35839090-9f656a9a-0b42-11e8-8173-08870d1601ff.png) ![image_4](https://user-images.githubusercontent.com/22040436/35839090-9f656a9a-0b42-11e8-8173-08870d1601ff.png)
Above is a picture of my Labrador’s software interface. I used the signal generator to output a 3V sin wave. As you can see, the yellow trace (oscilloscope CH1), is half the height of the blue trace (oscilloscope CH2). Thus, the voltage at Vout is half of the voltage at Vin! To test the theory, I loaded up the Labrador's software interface and generated a 3V sin wave using the signal generator CH1. As per above, oscilloscope CH1 (yellow trace) measures Vout, and oscilloscope CH2 (blue trace) measures Vin.
By eye, it appeared as though the yellow trace was about half the height as the blue trace. I looked at the max and mean voltages to confirm it, though; 0.681 is almost exactly half of 1.38, and 1.465 is almost exactly half of 2.92. Vout is almost exactly half of Vin.