Momentary Hi / Low switch Held High with resistor - How to add LED?
 

Hi,

I'd like to add an LED to the following circuit situation:

I have an input line that I hold high using a resistor tied to High.
The other side of the resistor is tied to one side of the momentary switch.
The other side of the momentary switch is tied to GND.

Toggling the switch shows LOW when pressed and HIGH when not pressed on a
Logic probe.
So far, so good.

If I add an LED to the switch (in parallel) it shows high (lit) and when the
button is pressed it goes off, but I lose the LOW signal on the logic probe,
indicating an OPEN condition.

Then I tried placing the LED from the HIGH / Resistor contact point, to GND.
Same problem.

How do I add an LED to a Momentary switch, tied HIGH (or low) via a
resistor, and maintain both HIGH and LOW signals without creating an OPEN
circuit?

Thanks,

Farce

Momentary Hi / Low switch Held High with resistor - How to add LED?
 

On 2006-07-15, Farce Milverk wrote:
Hi,

I'd like to add an LED to the following circuit situation:

I have an input line that I hold high using a resistor tied to High.
The other side of the resistor is tied to one side of the momentary switch.
The other side of the momentary switch is tied to GND.

Toggling the switch shows LOW when pressed and HIGH when not pressed on a
Logic probe.
So far, so good.

If I add an LED to the switch (in parallel) it shows high (lit) and when the
button is pressed it goes off, but I lose the LOW signal on the logic probe,
indicating an OPEN condition.

nope indicating an inbetween voltage.

best way is to put the led and resistor in parallel with the pull-up
resistor

+--|---[330]---+ T
| | ~~~
+5 +---[10k]-------+-+--o o------+ ground
|
+------ out

led goes on, out goes low, when button pressed


if you want the led to go out use a NC switch and turn the circuit round the
other way.



--

Bye.
Jasen

Momentary Hi / Low switch Held High with resistor - How to add LED?
 

I may be able to help. I did well in the digital class. But I am having
trouble understanding. Could you post a schematic? Well, a text-based
diagram?





"Farce Milverk" wrote in message
...
Hi,

I'd like to add an LED to the following circuit situation:

I have an input line that I hold high using a resistor tied to High.
The other side of the resistor is tied to one side of the momentary
switch.
The other side of the momentary switch is tied to GND.

Toggling the switch shows LOW when pressed and HIGH when not pressed on a
Logic probe.
So far, so good.

If I add an LED to the switch (in parallel) it shows high (lit) and when
the button is pressed it goes off, but I lose the LOW signal on the logic
probe, indicating an OPEN condition.

Then I tried placing the LED from the HIGH / Resistor contact point, to
GND. Same problem.

How do I add an LED to a Momentary switch, tied HIGH (or low) via a
resistor, and maintain both HIGH and LOW signals without creating an OPEN
circuit?

Thanks,

Farce

Momentary Hi / Low switch Held High with resistor - How to add LED?
 

On Sun, 16 Jul 2006 03:00:31 GMT, "¦¦¦SHADOW¦¦¦"
wrote:

I may be able to help. I did well in the digital class. But I am having
trouble understanding. Could you post a schematic? Well, a text-based
diagram?

---
I sense an aura of trollness about you.

Would you mind bottom posting in order to make at least a little of
that go away?

Thank you.



--
John Fields
Professional Circuit Designer

Momentary Hi / Low switch Held High with resistor - How to add LED?
 

What's trollness? Or bottom posting? It posts below the message I am
responding to (Outlook Express).
"John Fields" wrote in message
...
On Sun, 16 Jul 2006 03:00:31 GMT, "¦¦¦SHADOW¦¦¦"
wrote:

I may be able to help. I did well in the digital class. But I am having
trouble understanding. Could you post a schematic? Well, a text-based
diagram?

---
I sense an aura of trollness about you.

Would you mind bottom posting in order to make at least a little of
that go away?

Thank you.



--
John Fields
Professional Circuit Designer

Momentary Hi / Low switch Held High with resistor - How to add LED?
 

On Sun, 16 Jul 2006 13:32:11 GMT, "¦¦¦SHAD0W¦¦¦"
wrote:

What's trollness?

---
http://en.wikipedia.org/wiki/Internet_troll
---

Or bottom posting?

---
Post _below_ the article you're responding to.
---

It posts below the message I am
responding to (Outlook Express).

---
Frayed knot.

Look at your own replies.


--
John Fields
Professional Circuit Designer

Momentary Hi / Low switch Held High with resistor - How to add LED?
 

On 2006-07-16, ¦¦¦SHAD0W¦¦¦ wrote:

What's trollness? Or bottom posting? It posts below the message I am
responding to (Outlook Express).

Put your response under what you're responding to
and trim all the boring bits (like the signature)

Bye.
Jasen

Momentary Hi / Low switch Held High with resistor - How to add LED?
 

=

best way is to put the led and resistor in parallel with the pull-up
resistor

+--|---[330]---+ T
| | ~~~
+5 +---[10k]-------+-+--o o------+ ground
|
+------ out

led goes on, out goes low, when button pressed


if you want the led to go out use a NC switch and turn the circuit round
the
other way.



I will try this once more tomorrow - I could not get this to work, same
problem.

Momentary Hi / Low switch Held High with resistor - How to add LED?
 

On 2006-07-22, Farce Milverk wrote:
=

best way is to put the led and resistor in parallel with the pull-up
resistor

+--|---[330]---+ T
| | ~~~
+5 +---[10k]-------+-+--o o------+ ground
|
+------ out

led goes on, out goes low, when button pressed


if you want the led to go out use a NC switch and turn the circuit round
the
other way.



I will try this once more tomorrow - I could not get this to work, same
problem.

If it still gives you problems reduce the 10K to 1K.-

Bye.
Jasen