DIY - LM1881 Sync Stripper
This page will show you how to use an LM1881 chip to "strip" the sync information from composite video, for use
in an RGBs video signal. If you'd like to buy a pre-made sync stripper, please check out
The LM1881 has other uses, but this page is specifically showing how to get composite sync from composite video.
For more information on sync, please see the main sync page.
You will need basic tools (more info can be found in the tools section), plus the
following items for this circuit:
- Basic tools, such as pliers, tweezers, etc.
- Soldering iron / solder
- Basic soldering
- LM1881M chip, the SOIC version (please
see the links to the right for the chip) --->
- One 680K resistor:
- Two 0.1uf Capacitors:
This is a fairly easy circuit to build, but there's a few tricks to make it
smaller and easier. Also, this guide assumes you'd like to use a mounting board (thanks to the guys on the
neo-geo forum for the idea). You can use this guide if you'd like to
solder directly to a chip, but this is a "cleaner" way to make the circuit. I'll walk you through
- This is the main LM1881M chip you'll be using (surface-mount, SOIC version) and it's relevant pins:
- Start by adding solder to both the chip legs and the pads on the board, by heating the area with your
soldering iron and then touching solder to the metal. I got used to doing this on a desk, but using a stand
and alligator clips will make it easier:
- After applying solder to both, use pliers or tweezers to hold the chip while you mount it to the board.
Once it's lined up, you should be able to just touch your soldering iron to it and they will solder together:
- Next, you'll want to use a multimeter to check your solder points. When checking, make sure to touch the
pin where it enters the chip, not near the bottom where you may accidentally be making contact with the circuit
board's pads. Then, touch the other tester to the pad that matches it's input. If a connection isn't
made, you could try adding more solder to the joint between the pad and pin:
- Add a 0.1uf capacitor to the hole that corresponds with pin 2 (composite video in) on the
LM1881M. I suggest using a multimeter to double check that the hole on the board matches the pin on the
- Then add a 680K resistor to the holes corresponding to the arrows below (once again, I suggest using
a multimeter to double check the holes to pins between the chip and board). Also, make sure that the
resistor isn't touching any of the pins on the chip, or touching the other holes on the board. I have
mine run above the board to ensure it's not touching, as shown in the bottom-right picture:
- Next, solder a 0.1uf capacitor to the resistor. I like to solder it as close to the resistor itself as
possible, to make sure it's not touching anything else, or touching to board's pads.
- Finally, solder power and ground, as well as composite video in / csync out:
- After you're done, it's good to cover the circuit with heatshrink tubing, so you won't risk shorting it
out (or anything else around it).
- That's it! Overall, it's pretty easy to make and is a bit smaller then soldering it directly to the
chip. I actually fit one of these inside a VGA head and for use with my N64 and RGB dsub switch! Also, it makes for a much cleaner look. That being said,
if you prefer the chip-only solution, you can check out this guide:
That's it! A pretty easy circuit that can really come in handy! If you've arrived at this page as part of the RGB Guide, please move along to: what method you'd like to
use to display RGB. If not, feel free to head to the main sync stripper
page, or check out the homepage for everything else we have to