question with a 7 segments display

[poorboy]

Hi breakthru and everyone, Iam thinking about using a 2digit 7segment meter as a voltage meter but i dont have any idea where to start. Can someone help me with it? Is there an specific 7segment display i need to use? Resistors value and how to wire it. TIA

[CraigHB]

There's two types of segmented displays, LCD and LED.  Not sure which you're talking about.  In either case, you need a controller.  With three digits, that's 23 segments you'll need to control (two are period symbols).  An MCU can be used in either case.  There are also controller chips for that purpose that can be serially interfaced with an MCU.

LCD displays need higher voltage to drive the LCD so a charge pump is required.  It's usually included with a controller, but if you want to use an MCU, you'll need to add one.  The advantage of an LED segmented display over a LCD segmented display is you don't need the charge pump since you can usually bias the diodes with a supply as low as 3V.  The disadvantage is you need a set of bias resistors.  With an LCD, you only need one charge pump which is just a small chip and a capacitor.

[poorboy]

Thanks craig. What I want to use is a LED. It is a 2digit LED. And not sure how to have it working as a volt meter. A diagram would really be appeciated

[CraigHB]

Most people use the little voltmeter displays you can buy.  They're like two bucks on eBay.   Just two wires to hook up.  Is that what you're talking about?  Those you simply connect in parallel with the atomizer.  Add a switch inline to disable it when desired.  You can alternately use a double throw switch to check battery voltage or atomizer voltage.

If you want to build your own voltmeter, it's a bit involved.  Typically, you would only use a generic display if you want to build a battery mod that incorporates an MCU to do functions in addition to driving the display.

[poorboy]

I see. It's not for an MCU craig. The reason why i want to use this 2digit display is because of the enclosure Iam working on right now there isn't much room for the 3digit display. That why i want to ise a much smaller display and i found this 2digit display. If it's not really possible to have this 7segment led working on a vv mod i'll just throw it away. )