555/556 Problem

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CDRIVE

Joined Jul 1, 2008
2,219
We're up to post 77 so it gets quite laborious to sift through all the posts to find your most current schematic. For this reason it would be beneficial if you post the link to it. FYI, it would be nice to see the whole thing... including the relays. ;)
 

Thread Starter

CitrPug

Joined Feb 20, 2011
83
Can the 4069 fail in such a way to cause this?

I honestly can't see anything else in the circuit that might cause this.
 

CDRIVE

Joined Jul 1, 2008
2,219
I don't see anything glaringly wrong in your circuit. Do you still have this circuit on a protoboard? If so, disconnect the Reset pin from the V+ and reconnect it using a 10K resistor. This way you can ground the reset pin to see if the output goes low.
 

Thread Starter

CitrPug

Joined Feb 20, 2011
83
Still on a protoboard.

Both the outputs go low when they should, the problem is they both trigger and then go low at the same time rather than just one.

I'll try your suggestion, in the mean time - any other suggestions? Would a picture of the protoboard be helpful - just in case I have got something wrong or if something being in another place would make a difference.
 

SgtWookie

Joined Jul 17, 2007
22,210
Yes.

I suggest that you give up on this project.

If you can't fix it yourself when its' wired on a prototype board, how are you going to fix it when it breaks after you install it to control your folding wing mirrors on your car?

Besides, this Board does not support topics that involve automotive modifications, as stated in section 6 of the Terms of Service; links to which are on every page of this forum - but for your convenience, here it is again:
http://www.allaboutcircuits.com/l_tos.html

And the relevant section:
6. Restricted topics. The following topics are regularly raised however are considered "off-topic" at all times and will results in Your thread being closed without question:
  • Any kind of over-unity devices and systems
  • Automotive modifications
  • Devices designed to electrocute or shock another person
  • LEDs to mains
  • Phone jammers
  • Rail guns and high-energy projectile devices
  • Transformer-less power supplies
You did not mention in this thread that it is an automotive application, but your prior two threads (one of which was closed) did specifically mention that it IS intended for an automotive application.
1st thread: http://forum.allaboutcircuits.com/showthread.php?t=50293
2nd thread: http://forum.allaboutcircuits.com/showthread.php?t=52502

Even if you DO make it work on the bench, it is very likely to fail after you install it, as there are no protections provided for the kind of transient voltages seen on automotive electrical systems, particularly during occurrences known as "load dumps".

If you insist on continuing with this project anyway, you must do so elsewhere - not on these forums.
 
Last edited:

bertus

Joined Apr 5, 2008
20,226
Hello,

SgtWookie is right with the violation of the Tos.

I am closing this thread as it violates AAC policy and/or safety issues.

Quote:
6. Restricted topics. The following topics are regularly raised however are considered “off-topic” at all times and will results in Your thread being closed without question:

  • Any kind of over-unity devices and systems
  • Automotive modifications
  • Devices designed to electrocute or shock another person
  • LEDs to mains
  • Phone jammers
  • Rail guns and high-energy projectile devices
  • Transformer-less power supplies
This comes from our Tos:
Terms of Service
There will be enough sites where automotive questions can be discussed :
Member selected automotive forums

Bertus
 
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