?s on identifying a 555 timer chip

[Dave]

Here's one... If I had a circuit that made use of a 555 timer chip, but it
was not marked in any way that I could identify as the markings or a 555,
how could I confirm that it was indeed a 555 timer chip? Still working on
wireless remote for automatic door opener that doesn't. I believe I have
confirmed proper function in the three transistors, but it looks like the
oscillator isn't doing its thing. Power to the antenna goes up when the
switch is depresssed, but it doesn't come back down like it used to, back
when it gave me a nice 10kHz square wave. Now I am wondering if the chip is
a 555 timer that is for some reason malfunctioning...

Many thanks for any help.

Dave

 

[John Fields]

On Thu, 19 Jun 2014 04:14:50 -0500, "Dave" <db5151@hotmail.com>
wrote:

Here's one... If I had a circuit that made use of a 555 timer chip, but it
was not marked in any way that I could identify as the markings or a 555,
how could I confirm that it was indeed a 555 timer chip?

---
"Reverse engineer" the circuit by checking continuity visually,
and/or with an ohmmeter, in order to determine the paths of the
traces leading to and from the chip and making a map (schematic) of
what pin numbers on the chip lead to which components and how
they're all interconnected.

John Fields

 

[Jasen Betts]

On 2014-06-19, Dave <db5151@hotmail.com> wrote:

Here's one... If I had a circuit that made use of a 555 timer chip, but it
was not marked in any way that I could identify as the markings or a 555,
how could I confirm that it was indeed a 555 timer chip?

9 pins power supply positive to pin 8 negatve to pin 1
output from pin 3 or 5 (all the other pins are inputs of different
types)

Still working on wireless remote for automatic door opener that doesn't.
I believe I have confirmed proper function in the three transistors, but
it looks like the oscillator isn't doing its thing.

that seems unlikely.

--
umop apisdn

 

[Michael Black]

On Thu, 19 Jun 2014, Dave wrote:

Here's one... If I had a circuit that made use of a 555 timer chip, but it
was not marked in any way that I could identify as the markings or a 555,
how could I confirm that it was indeed a 555 timer chip? Still working on
wireless remote for automatic door opener that doesn't. I believe I have
confirmed proper function in the three transistors, but it looks like the
oscillator isn't doing its thing. Power to the antenna goes up when the
switch is depresssed, but it doesn't come back down like it used to, back
when it gave me a nice 10kHz square wave. Now I am wondering if the chip is
a 555 timer that is for some reason malfunctioning...

Get the datasheet or application note, and compare a sample circuit with
what you trace on the board. I'm not sure you can ever be absolutely
certain, but if it matches, it is most likely a 555.

Michael

 

[Dave]

"John Fields" <jfields@austininstruments.com> wrote in message
news:d9e5q91g0di2qi12cgaj0t5uqrvck9590q@4ax.com...

On Thu, 19 Jun 2014 04:14:50 -0500, "Dave" <db5151@hotmail.com
wrote:

Here's one... If I had a circuit that made use of a 555 timer chip, but
it
was not marked in any way that I could identify as the markings or a 555,
how could I confirm that it was indeed a 555 timer chip?

---
"Reverse engineer" the circuit by checking continuity visually,
and/or with an ohmmeter, in order to determine the paths of the
traces leading to and from the chip and making a map (schematic) of
what pin numbers on the chip lead to which components and how
they're all interconnected.

John Fields

Yeah, that's what I'm doing, but was hoping there might be some simpler
method of confirming the chips identity. Will keep at it. Thanks...

Dave

 

[Dave]

"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:lnujq8$191$3@gonzo.reversiblemaps.ath.cx...

On 2014-06-19, Dave <db5151@hotmail.com> wrote:
Here's one... If I had a circuit that made use of a 555 timer chip, but
it
was not marked in any way that I could identify as the markings or a 555,
how could I confirm that it was indeed a 555 timer chip?

9 pins power supply positive to pin 8 negatve to pin 1
output from pin 3 or 5 (all the other pins are inputs of different
types)

Still working on wireless remote for automatic door opener that doesn't.
I believe I have confirmed proper function in the three transistors, but
it looks like the oscillator isn't doing its thing.

that seems unlikely.

--
umop apisdn

What seems unlikely? That the three transistors are functioning properly,
or that the oscillator is malfunctioning? I'm curious...

Dave

 

[Dave]

"Michael Black" <et472@ncf.ca> wrote in message
news:alpine.LNX.2.02.1406191306510.16630@darkstar.example.org...

On Thu, 19 Jun 2014, Dave wrote:

Here's one... If I had a circuit that made use of a 555 timer chip, but
it
was not marked in any way that I could identify as the markings or a 555,
how could I confirm that it was indeed a 555 timer chip? Still working
on
wireless remote for automatic door opener that doesn't. I believe I have
confirmed proper function in the three transistors, but it looks like the
oscillator isn't doing its thing. Power to the antenna goes up when the
switch is depresssed, but it doesn't come back down like it used to, back
when it gave me a nice 10kHz square wave. Now I am wondering if the chip
is
a 555 timer that is for some reason malfunctioning...

Get the datasheet or application note, and compare a sample circuit with
what you trace on the board. I'm not sure you can ever be absolutely
certain, but if it matches, it is most likely a 555.

Michael

Hadn't thought of that. Thanks. Will look at the options. Much
appreciated...

Dave

 

[Jasen Betts]

On 2014-06-20, Dave <db5151@hotmail.com> wrote:

"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:lnujq8$191$3@gonzo.reversiblemaps.ath.cx...
On 2014-06-19, Dave <db5151@hotmail.com> wrote:
Here's one... If I had a circuit that made use of a 555 timer chip, but
it
was not marked in any way that I could identify as the markings or a 555,
how could I confirm that it was indeed a 555 timer chip?

9 pins power supply positive to pin 8 negatve to pin 1
output from pin 3 or 5 (all the other pins are inputs of different
types)

Typo: 8 pins

Still working on wireless remote for automatic door opener that doesn't.
I believe I have confirmed proper function in the three transistors, but
it looks like the oscillator isn't doing its thing.

that seems unlikely.

--
umop apisdn


What seems unlikely? That the three transistors are functioning properly,
or that the oscillator is malfunctioning? I'm curious...

a combination of a 555 and discrete transitors comprising a remote control.


--
umop apisdn


--- news://freenews.netfront.net/ - complaints: news@netfront.net ---

 

[Dave]

"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:lo0gnm$du0$2@gonzo.reversiblemaps.ath.cx...

On 2014-06-20, Dave <db5151@hotmail.com> wrote:

"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:lnujq8$191$3@gonzo.reversiblemaps.ath.cx...
On 2014-06-19, Dave <db5151@hotmail.com> wrote:
Here's one... If I had a circuit that made use of a 555 timer chip,
but
it
was not marked in any way that I could identify as the markings or a
555,
how could I confirm that it was indeed a 555 timer chip?

9 pins power supply positive to pin 8 negatve to pin 1
output from pin 3 or 5 (all the other pins are inputs of different
types)

Typo: 8 pins


Still working on wireless remote for automatic door opener that
doesn't.
I believe I have confirmed proper function in the three transistors,
but
it looks like the oscillator isn't doing its thing.

that seems unlikely.

--
umop apisdn


What seems unlikely? That the three transistors are functioning
properly,
or that the oscillator is malfunctioning? I'm curious...


a combination of a 555 and discrete transitors comprising a remote
control.

Aah. Well, the device only sends a brief radio signal to the door opener,
whereupon the door opener opens the door. Not really much of a remote, but
it does the job needed.

And it does, so far, look like the chip is a 555, but I'm not through yet. I
am just glad that if this chip is what I think it is, which is a CMOS 555, I
can pick that up at the local Radio Shack. They do still carry that much.

D

 

[Michael Black]

On Fri, 20 Jun 2014, Dave wrote:

"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:lo0gnm$du0$2@gonzo.reversiblemaps.ath.cx...
On 2014-06-20, Dave <db5151@hotmail.com> wrote:

"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:lnujq8$191$3@gonzo.reversiblemaps.ath.cx...
On 2014-06-19, Dave <db5151@hotmail.com> wrote:
Here's one... If I had a circuit that made use of a 555 timer chip,
but
it
was not marked in any way that I could identify as the markings or a
555,
how could I confirm that it was indeed a 555 timer chip?

9 pins power supply positive to pin 8 negatve to pin 1
output from pin 3 or 5 (all the other pins are inputs of different
types)

Typo: 8 pins


Still working on wireless remote for automatic door opener that
doesn't.
I believe I have confirmed proper function in the three transistors,
but
it looks like the oscillator isn't doing its thing.

that seems unlikely.

--
umop apisdn


What seems unlikely? That the three transistors are functioning
properly,
or that the oscillator is malfunctioning? I'm curious...


a combination of a 555 and discrete transitors comprising a remote
control.


Aah. Well, the device only sends a brief radio signal to the door opener,
whereupon the door opener opens the door. Not really much of a remote, but
it does the job needed.

And it does, so far, look like the chip is a 555, but I'm not through yet. I
am just glad that if this chip is what I think it is, which is a CMOS 555, I
can pick that up at the local Radio Shack. They do still carry that much.

Though apparently not for much longer, elsewhere they seem to be doing a
countdown as to how long the chain will last, according to some, the count
is in days.

Of course, there was the period here when someone asked about a 555 that
they'd be told to "use a PIC", so even something with only eight pins
could be something vastly more complicated. That would allow a much more
complicated signal.

Michael

 

[ehsjr]

On 6/19/2014 8:07 AM, Jasen Betts wrote:

On 2014-06-19, Dave <db5151@hotmail.com> wrote:
Here's one... If I had a circuit that made use of a 555 timer chip, but it
was not marked in any way that I could identify as the markings or a 555,
how could I confirm that it was indeed a 555 timer chip?

9 pins power supply positive to pin 8 negatve to pin 1
output from pin 3 or 5 (all the other pins are inputs of different

Typo, change 5 to 7

 

[greenaum]

It's a good idea. A resistor and capacitor between pins x, y, and z,
etc, is your standard 555 circuit. Presumably it's either an astable
to generate a frequency, or a monostable to send a pulse that makes
the transistors oscillate for a set time. 555 oscillator circuits tend
to all look very similar so you could figure it out from that. Get a
circuit for one, and see if the pins are connected to similar
combinations of components.

--

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Which Alice did not venture to deny.