LM1881 Sync Stripper
A note: Only use this guide if you need a "loose" chip. Using a surface-mount version will be a bit
smaller and in most cases be a better solution. You can find more info on that in this guide. Also, if you'd like, you can buy a pre-made sync stripper on this page.
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. 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
- LM1881 chip (please see the links to the right for the chip) --->
- One 680K resistor:
- Two 0.1uf Capacitors:
- Start with the chip itself. You'll want to make sure the circle on the top of the chip is always aligned
the way you see in these pictures:
- Straighten all the legs and remove the unused pins as shown below. You can cut or bend the pins
- I like to trim the excess off the end of the pins. This is also a good time to add solder to each
- Trim the length of the 680k resister and solder it to the pins as shown below:
- Turn the circuit over (note the orientation of the pins!) and get ready to solder the capacitor. This
part is a bit tricky...trim and solder the 0.1uf capacitor to the resister, however you need to get the
capacitors legs as close to the actual resister as you can. You need to make sure the capacitor legs aren't
touching anything else except the resister. Then, fold the capacitor over onto the LM1881.
- Here's an example of both the proper and improper way to install the capacitor, but much more spread out, so
it's easier to see. Please note on the "good" picture the capacitor is only touching the resistor and on the
"bad" picture, both the capacitor and resistor are touching the LM1881 chip:
- Next, turn the chip back over to it's original orientation (note the circle in the upper left). Solder
the second 0.1uf capacitor to the middle leg of the LM1881. I trimmed and bent the capacitor's leg, so it could lay
flat on the LM1881. Please note the capacitor's other leg is above the LM1881, not touching it.
- Solder your wires to the points as shown below. You'll need power (the chip can handle 5-12 volts, but I
always use a 5v source), ground and composite video to the chip, then you can solder composite sync-out to
your RGB connector:
- Here are some examples of finished LM1881 circuit's done slightly different. The one on the left is the
exact same as this mod, but both capacitors are on the same side. The one on the right was used inside a
console that had lots of extra space, so I was able to spread it out, making it slightly easier to assemble:
- After you're done, it's good to cover the circuit with heatshrink tubing, or non-conductive tape, so you
won't risk shorting it out (or anything else around it).
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