Read voltage

<iframe width="450" height="260" style="border: 1px solid #cccccc;" src="https://thingspeak.com/channels/281407/charts/1?bgcolor=%23ffffff&color=%23d62020&dynamic=true&results=60&type=line&update=15"></iframe>

<iframe width="450" height="260" style="border: 1px solid #cccccc;" src="https://thingspeak.com/channels/281407/status/recent"></iframe>