common anode and common cathode differences in 7segment display

What are the changes need to do when using common anode seven segment display instead of common cathode seven segment display. hint:use transistors?

Question by nethmi.amanda.3344   |  last reply


Multiplexing more than 100 7segment LED displays with a microcontroller

What are the multiplexing techniques to interface about 100 7segment displays to a 8-bit microcontroller (say 8051). If I hook up a row of decoders to the control pins of the display array on a common bus, I guess I might acheive it. But I doubt if there would be any flicker while doing so. Say for example, If I have 64 pairs of 7seg digits to be controlled, I may do a round-robin multiplex to the tune that each pair is ON for about 1ms in every 64 ms. Will that be possible, given that the duty cycle and frequency are of that order? Thanks for your invaluable response. Regards, Ather

Topic by blue_flare 


Fluctuating voltage?

I am trying to build an ammeter using a 100:5A CT and a pic16F716 and display the value using 7segments. However, The voltage I get from the CT after rectifying it using an OPAMP still fluctuates between 4.8 and 5.4 .  I don't understand what is causing it to fluctuate that way. I will attach a picture of the circuit I am working on.

Question by IndiraK2   |  last reply


calculating MAX7219 resistor value?

I want to use the 7219 to drive two 3digit 7segment displays with these specs. I want to use 1.85v and 18mA. Here's what the MAX7219 datasheet states as resistor values to be used. I'm too dumb to figure out how the resistor value is calculated. Can someone help? What would the resistor value be for 1.85v 18mA?

Question by DELETED_MakiY2   |  last reply


What is a good schematic for a multimeter with an attiny85v and some 7 segment leds?

I want to make a multimeter out of an attiny85v, and some 7segment leds for a 12volt power supply that I made, I would like it to measure from 0.0V to 12.0 volts, with an accuracy of .1 volts. Anyone know any good circuits? EDIT: This is what I am looking for, except the author has not included any code http://fedetft.wordpress.com/2010/10/02/digital-voltmeter-for-power-supply/

Question by Michael_Bell   |  last reply


How do you code an arduino to count and display on LCD each number every time a relay triggers? Answered

OK, I'm kinda new at the programming part for my projects. I was wondering if anyone can help me with (what I assume will be a simple code for a veteran) a code for arduino and maybe with a little explanation of the code. Project is simple. I have a toy laser gun shooting at a target with a photocell attached and connected to a relay. What I would like is that every time the relay switches, a counter adds the shot so I can keep score. It's for my son's 9th birthday party and I've already built the targeting range (with  Lego Movie theme) and even some servos to knock back guys down.  I just need a way to keep score. I have some Arduino Uno's, some nanos, some trinkets, some LCDs (2X16 and 4X8) and 4X 7segment displays so I have some options for parts,but at the moment I do not have a lot of time to go through a self-learning curve to get the coding to work.  Can anyone please help?  It would be greatly appreciated. Thanks.

Question by jedii72   |  last reply