Rotory encoder chip ?

Several are available from usdigital.com.

-- Gordon

You can use a D type flip flop and some gates. Put one phase into the data input, and put the other phase into the clock, this will give you your direction bit, and then use a couple AND gates to gate one of the phases.

Thanks for the tip. After thinking about it I came to the conclusion that it really should be easy with an edge clocked IC and maybe some logic. I just didn't want to think that hard :-) I think that the direction pulses will be what I use (two leads instead of three). Getting old is tough.

Bill K7NOM

How old are you? I'm 43 this year :-(

Well, if that's what you are going to do, you can run the two phases into an XOR gate and increase the resolution.

Bill,

I second Gordon's recommendation of US Digital. They have an 8-pin chip that does exactly what you want, and they are inexpensive. I bought several, and found them quite easy to use.

Jeff.

Gord>>

I went to their web page and didn't find info on the chip - will look again

Bill K7NOM

I hope I am as in possession of my faculties, let alone breathing, when I am

Try here:

Even if you have the ICs to make your own decoded out of gates in your junk bin, there are a number of advantages to this particular chip, apart from a smaller footprint on your board. The chips include signal conditioning and debouncing, useful to prevent jitter that can occur at an edge boundary. Also you can easily switch between 1X, 2X, and 4X counting, which gives you greater flexibility. An external resistor (you can also use a 10M pot in parallel with a 5K resistor) allows you to easily set a pulse width, saving you from creating one using a 555, RC network, or whatever.

-- Gordon

Thanks , that is what I had in mind. I will order a couple - 1 to use and 1 to burn up ;-)

Bill K7NOM

Since the shipping costs will probably be equal to the cost of the two chips, you might also look at their Miniature Optical Kit Encoder, a $20 quadtrature encoder that can connect directly to a motor shaft. While I've also done the homebrew stuff, I like the kit because the resolution goes up to 300 CPR (therefore 1200 counts at 4X resolution), which really solves a lot of little problems. The thru-hole variation allows you to attach it directly to the motor, between the motor and wheel/sprocket/gear. Nifty stuff. I've retrofitted several devices with quad encoders with these.

-- Gordon