Line drivers & level restorers

[RussMartin]

Has anyone tried driving multiple parallel lines, each with an inverter (e.g., 74xx04, 74xx14), then using another inverter at the opposite end to restore the polarity and level? If so, what was your maximum distance?

[Ioannis]

I tried the Wiegand interface which is similar and maybe more difficult from the aspect that the line sits at +Vdd and drops low for 20 microseconds for every pulse transmitted.

It worked OK for 20 meters and the spec's say for over 100. A friend of mine tested this to be true.

So I believe with just an inverter or maybe a schmitt trigger even better resuts are to be expected.

Also a resistor (470-1200 ohm) at the end line to +Vdd will help.

Ioannis

[RussMartin]

Also a resistor (470-1200 ohm) at the end line to +Vdd will help.

So . . . a pull-up on the input at the receiving end?

[hatchethand1000]

I am currently driving from a pic pin through a 10k resistor to a pn2222a, base with the collector on ground and the emitter tied with 10K resistor to 5v. From the emitter out I am able to drive up to 300 ft to a similar circuit on the other end. In this configuration it is inverted and driven a good distance.

The 7414 with the schmit triggered input will restore a very similar output to the other end, inverted from the single input on the '14.

I am using this circuit configuration for PS/2 communication, works well.

K

[Ioannis]

So . . . a pull-up on the input at the receiving end?

Yes, that's right.

hatchethand1000:

I was a little confused by your configuration. Are you sure about this? It seems you have reverse biased the transistor.

Ioannis