voltage level shifting

Hi, Could anybody advise how to perform voltage level shifting. We have got two encoder channels: A and B coming from two Hall Sensors.
Unfortunetely, the system (Advantech board) can only recognise one of these channels since the voltage levels are different.
Encoders channel A (readable): Low: ~0.07V High: ~4.9V
and
Encoders channel B (nonreadable): Low: ~1.66V High: ~4.9V
In order to make channel B readable for the system, I need to reduce the voltage low level to <0.8V because the system digital input is specified as follows:
max. low level: 0.8V min. high level: 2.0V
Any ideas how I can achieve this easily?
Thanks Daniel
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@bris.ac.uk wrote:

Several:
Feed the signal through a comparator with a suitable threshold and standard TTL-level output.
Feed _both_ signals through identical comparators do avoid differential delay at high rates.
Use CMOS buffers -- inverting or not -- instead of comparators.
Repair Channel B. It is defective.
Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Apr 28, 4:08 am, snipped-for-privacy@bris.ac.uk wrote:

Hi, Daniel. Channel B is very likely defective, as mentioned in another post. That means replacing the encoder or the hall effect sensor. However..
In order to be sure, you should do some checking. Most hall effect sensors have open collector outputs. That will mean a logic level low (<0.8V for sure) if the current draw is less than 20mA. Your high voltage = 4.9V doesn't contradict that. You should look and see if you have pullup resistors installed on the Advantek board -- the one for the B channel might be wrong, say 100 ohms instead of 1K or 10K. You should also check your wiring to the board. Many of these connectors are a pain, and it's easy to miswire or have two or more wires accidentally short when you put the clamshell over the connector.
Another thing you might try is just connecting a 100 ohm resistor from the Advantek input to GND and see how much current it draws by measuring the voltage across the 100 ohms and using ohms law.
These intermediate steps are important, because if you buy a replacemnt without fixing a problem, you might smoke another one and have to buy two.
Good luck, and hope you don't replace anything expensive unless you have to.
Cheers Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks Jerry and Chris. I will try my best to solve the problem based on your suggestions. As soon as I have got new results, I will give u an update. Thanks again and best wishes Daniel
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 30 Apr, 15:30, snipped-for-privacy@bris.ac.uk wrote:

Hi Jerry and Chris, Finally, the supplier of the encoder confirmed that the Hall Sensor (channel B) is defect. Thanks again Daniel
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.