I need to switch a 0.5V to 0.5 to 5.5V seamlessly

  • Thread starter Thread starter Dan King
  • Start date Start date
  • Tags Tags
    Switch
Click For Summary

Discussion Overview

The discussion revolves around the challenge of seamlessly switching a signal from 0.5V to a range of 0.5 to 5.5V in an automotive application. The focus is on finding a solution using available components to manipulate the signal for an ECU during vehicle acceleration.

Discussion Character

  • Technical explanation, Experimental/applied, Debate/contested

Main Points Raised

  • One participant describes the need to manipulate a signal to prevent engine revving while accelerating, suggesting that the task should be feasible.
  • Another participant recommends looking into analog switches or analog multiplexers as potential solutions.
  • A participant expresses urgency in completing the project using available components like Op-Amps and FETs, indicating a time constraint due to upcoming customer visits.
  • There is a suggestion to contact local electronics stores or hobbyists for components, along with a specific part number (CD4051) for reference.
  • It is noted that many analog switches utilize FETs in linear mode, with links provided for further reading on the topic.
  • One participant raises a consideration regarding the use of an SPDT relay, mentioning potential issues with glitching during the switching process.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a specific solution, as multiple approaches are suggested, and the discussion remains open to various methods of achieving the desired signal manipulation.

Contextual Notes

Participants express uncertainty regarding the effectiveness of different components and configurations, and there are indications of potential issues with glitching when using relays.

Dan King
Messages
8
Reaction score
0
I'm working on a circuit to manipulate an existing signal for an automotive hydraulic hybrid product.

I need to pass on a 0.46 to 0.55V signal to the ECU during accelereration to keep the engine from revving and restore the original signal (0.55 to 5.5V) when the engine takes over.

This would be easy but I only have one position on my connector left.

Basically I need to make the ECU think that the truck is idling while accellerating and then take over and function normally.

Maybe I'm being a bonehead, but it seems this should be possible.

I won't complicate this more with the other accellerator input.
 
Engineering news on Phys.org
Look up analog switch / analog multiplexer.
 
That is the kind of thing I need. Just trying to get it done by Monday with the parts we have laying around: Op-Amps, FET's, etc. New customers are coming this week so I need to get something working.

Thanks for the reply.
 
Dan King said:
That is the kind of thing I need. Just trying to get it done by Monday with the parts we have laying around: Op-Amps, FET's, etc. New customers are coming this week so I need to get something working.

Thanks for the reply.

I'd hit the phones and call up the Radioshacks (a few may still carry components), components places, and friends who are electronics hobbyists around you locally. That or bite the bullet and pay for same-day shipping from DigiKey or Mouser.

I'd also go armed with a part number, for instance, CD4051:
http://www.fairchildsemi.com/ds/CD%2FCD4051BC.pdf

Good luck!

EDIT: Note that many analog switches are made from FETs in linear mode:
http://en.wikipedia.org/wiki/MOSFET#Single-type_MOSFET_switch
http://people.seas.harvard.edu/~jones/es154/lectures/lecture_4/mosfet/mos_circuits/cmos_gate/maxim/maxim.html

However, you may have to fiddle with the circuit so that it works properly...

Alternately, you might consider an SPDT relay, however, you might end up with a split second of glitching (if that's a significant issue) when the relay is switching from one contact to the other, and no connection exists.
 
Last edited by a moderator:

Similar threads

How can I reroute multiple signals from a 4 pin connector using a relay switch?
  • · Replies 37 ·
2
Replies
37
Views
7K
What hardware would I need to distribute a binary signal?
  • · Replies 5 ·
Replies
5
Views
2K