Jump to content
Electronics-Lab.com Community

volume attenuator relay


Recommended Posts

Hello.
I would like to make a volume attenuator composed of bistable single coil latch relays in logarithmic resistor ladder configuration.
to do this I thought of using a binary counter 40193 whose outputs go to an operational amplifier. the function of the operational amplifier is to send a pulse to the TC4420 half-bridge mosfet (attention, only one pulse at each change of state of the 40193) which controls the relay coil. to drive the bistable latch relays it is customary to use a pulse in one direction or the other without leaving the coil under voltage all the time.
as you can see from the attached image the other end of the coil is connected to the zero of the dual power supply.
to simplify, only one component of each type appears in the image (opamp, tc4420, relay), but in the real circuit there are at least six.
the problem is the following:
which op amp should i use? and which configuration is the most suitable?

quale OPAMP.jpg

doppia alimentazione x schmitt trigger.jpg

Link to comment
Share on other sites

i noticed a problem.
when the opamp does not work its output is at zero volts, this state does not agree with the TC4420 because it contains logic gates whose outputs cannot be at zero but high or low.
https://ww1.microchip.com/downloads/en/DeviceDoc/21419D.pdf
so i think the only solution is to use push pull transistor or mosfet or darlington.
do you confirm?

Link to comment
Share on other sites

As the TC4420 accepts logic level inputs and the  40193 output is a logic level why is anything needed between them? Also both  only require a single voltage supply (Vdd) for the circuit shown a dual supply would not be required. There are single Vdd supply op amps  if you need  one.

I have a circuit that uses a TC4420 driven directly via a Arduino Uno output.

Link to comment
Share on other sites

Step 1:

Are you committed to using to using the TC4420 and 40193?  Consider using a circuit like the one below. The direction of current flow  through the relay coil depends on which transistor is on.  Also if you do not have the relays yet these may simplify your design:

https://www.amazon.com/SMAKN-Trigger-Switch-Latching-controlled/dp/B01CN7V0F6/ref=sr_1_20?dchild=1&keywords=latching+relay&qid=1617978673&sr=8-20

What are you using of inputs to the circuit?

circuit2.png.81276c70dd66da161c5056911108d688.png

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

×
  • Create New...