Jump to content
Electronics-Lab.com Community
Sign in to follow this  
bonanz

Led display Digital Voltmeter question

Recommended Posts


Has anybody made this very old project work properly?
It will probably work properly if it is built according to the datasheet for the IC.


I brought a kit from Velleman which was based om the ICL7107 and I found that this gave unstable readings and could never cure the bouncing of the readings, May be this is why they stopped selling it ?

So in the end I decided to design and build my own based on the MAX7219 and PIC16F876, This gives accurate and stable readings and is now used in my Velleman PSU 0-30V 0-10A, I used ISIS to simulate it to get everything working(Picture attached) and then designed and built the PCB for it.
I like the idea of LED'S because where my PSU sits at the back of the bench I don't have to lean forward to see the LCD version. Plus I use the green version which is better

post-44828-14279144265204_thumb.jpg

Share this post


Link to post
Share on other sites

There are two versions of the old ICL7107 IC. The newer version ICL7107S has improved Stability.

The LED display draws up to 224mA through the IC which heats it a lot and causes it to drift.
It needs an additional -5V supply but you don't say how you produced it.

The L7805 regulator must have the two small capacitors shown on its datasheet. It needs a minimum input of +7V so the average rectified and filtered voltage must be more, depending on how much ripple is produced by the filter capacitor.
If the rectifier is full-wave then a 1000uF filter capacitor reduces the ripple to 1V peak. The transformer should be 8VAC or more at 500mA.

Im using the the ICL7107 CLP version,
i have produce the -5 volt with IC ICL7660

Share this post


Link to post
Share on other sites



I brought a kit from Velleman which was based om the ICL7107 and I found that this gave unstable readings and could never cure the bouncing of the readings, May be this is why they stopped selling it ?

So in the end I decided to design and build my own based on the MAX7219 and PIC16F876, This gives accurate and stable readings and is now used in my Velleman PSU 0-30V 0-10A, I used ISIS to simulate it to get everything working(Picture attached) and then designed and built the PCB for it.
I like the idea of LED'S because where my PSU sits at the back of the bench I don't have to lean forward to see the LCD version. Plus I use the green version which is better

hi Picmaster is it  posible from you to post the schematic and pcb of this volmeter of yours? ( PIC based)

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...