Project is an electro/mechanical clock the closes a contact every 30 secs. I wish to connect it to a dial mech that requires a pulse of alternating polarity every 30 seconds. Yesterday I cleaned up the the pulse with a 555, and with the aid of a 4013 & 4011 produced the neccessary drive pulses. ( about 300 Ms) All working on 5v. The H bridge was on a small Chinese module. I got no output from it to the clock motor.
Spent a long time testing.. Put LED's on the output of the driver circuit indicate it works.
A 6v bulb on the output of the H-bridge indicates that it responds to test inputs on wires to the 5v supply. I'm stumped.
Any theories or experience driving this chip appreciated.

 

Could you post a link to the data sheet for the H-bridge module?

Are you driving the module's input directly from... what? The 4013? The 4011? A schematic would sure help.

Also, 300 Ms is just a bit shy of ten years. I'm guessing that's not what you meant.

 

Hi c,
Is this module you have, or just the IC.?
E
Added the IC PDF.

 

Here's the circuit of the driver. It's a circuit I used 7 years ago in another clock that's worked faultlessly ever since. The h-bridge module was a different one though. The clock signal comes in via the 555 monostable which is another module by Mitch Electronics. Standard circuit I imagine.

 

Hi c,
Is this module you have, or just the IC.?
E
Added the IC PDF.

Yes Eric.. That's the module I'm trying to use..

 

@WBahn.. 1/3 second pulse duration from 555..sry ;-)
Data sheet as Ericgibbs's post.. Roger

 

In the driver circuit above I accidentally left in the clock as 1pps. That was as was in the design I copied.. but of course in this case its 2 pulses per minute.. sry ..very old brain at work ! R

 

hi Roger,
Is the problem solved.?
E

 

hi Roger,
Is the problem solved.?
E

No Eric.. I've got visitors for a few days so can't get back to it.. hence took this option ;-)

 

I don't know if this makes a difference in your circuit, but the L9110 has a unique feature compared to other H-bridge chips.

If both inputs are LOW, both outputs are LOW.

Unlike other H-bridge chips however, if both inputs are LOW, both outputs are also LOW, rather than HIGH as you'd expect.

I don't remember exactly what I was working on when I found this quirk.

 

Hi.. Sorry for delay.. I gave up on that project for a while while I waited for a replacement H bridge module to arrive.
Jon.. I think you meant if both inputs are HIGH.... as per the circled truth table ! However the driver circuit should alway present 2 lows except when a high pulse appears alternately on 1A and 1B.
Anyway.. now it now all works !! The replacement H bridge made no difference. I'm not sure if it was the main culprit, but the 555 monostable on the system 5v supply only sent a HIGH to the 4013 that was marginal as a cmos signal.
Also ( and maybe because of that ) the 4011 output drives were less than 3v (but enough to light a green led) The whole thing was on a breadboard so an intermittent connection can't be ruled out.
I replaced the 4011 and upped the sytem supply to 9v - but dropped the supply to the cmos driver board by about 2v via a red LED
Now all works fine. I haven't the patience to go back to the original setup stage by stage to actually confirm where the problem lay ;-) Thanks to all who replied.. Roger

 

Oops. Yes, I meant both inputs high.

Glad you got it working.