Amateur alarm circuit problem

RobH <rob@despammer.com> wrote:
> On 24/11/2020 08:41, Andy Burns wrote:
>> RobH wrote:
>> 
>>> This is why I hate asking questions here. No help, just castigated.
>> 
>> You're asking people to compare a schematic circuit diagram to a 
>> breadboard built circuit, that's over the threshold most people are 
>> willing to get into.
>> 
>> Why not provide a similar schematic showing your alterations?
>> 
>> 
> Ok, I take your point.
> 
> I have added the 10k pot, led and ldr onto the original schematic.
> It's the best I can do, I'm afraid, and hope it's clear enough.
> 
> https://drive.google.com/file/d/1ObLBgJfce4fMPrvRTk5emIRcJzxhNWOt/view?usp=sharing

It is miles better than your textual description in your original post.

Here is what you said initially:

> so I added an led through a resistor, a 10k pot and a LDR.  I then 
> connected the centre pin of the 10k pot to pin 2 on the top IC555 
> shown on the schematic

However, your new schematic above does *not* show the center pin of the 
10k pot connected to pin 2 of the top 555.  It shows the center pin of 
the 10k pot connected to the positive voltage rail, and the positive 
voltage rail connected to pin 2 of the 555.  Note also that your
annotations are wrong.  You have the line to pin 2 annotated as "to 
pin 3" and the wire to pin 3 annotated as "to pin 2".

So, either your textual description is wrong, or your new schematic 
drawing additions are wrong.  But you can't expect anyone here to be of 
much help when you provide incorrect information at the outset.

If you've built the circuit like you show in the new schematic, the top 
555 will not do anything, because pin 2 is the trigger input, and you 
have it shown as strapped to the positive voltage rail.  So the upper 
555 simply will not oscillate.

Also, your schematic shows no bypass capacitors for the 555's.  You've 
left out another critical bit of information.  Are you using bipolar 
555's or CMOS 555's?  Because if you are using bipolar 555's, you'll 
very much want to add bypass cap's across the 555 power rails.

Also, another tip, when positing schematic pictures here asking for 
help, it is best to add numbers to all the components (i.e., R1, R2, 
C1, C2, U1, U2, ...).  That helps you and us have a common nomenclature 
with which to refer to specific items on the schematics.

On 24/11/2020 16:43, Rich wrote:
> RobH <rob@despammer.com> wrote:
>> On 24/11/2020 08:41, Andy Burns wrote:
>>> RobH wrote:
>>>
>>>> This is why I hate asking questions here. No help, just castigated.
>>>
>>> You're asking people to compare a schematic circuit diagram to a
>>> breadboard built circuit, that's over the threshold most people are
>>> willing to get into.
>>>
>>> Why not provide a similar schematic showing your alterations?
>>>
>>>
>> Ok, I take your point.
>>
>> I have added the 10k pot, led and ldr onto the original schematic.
>> It's the best I can do, I'm afraid, and hope it's clear enough.
>>
>> https://drive.google.com/file/d/1ObLBgJfce4fMPrvRTk5emIRcJzxhNWOt/view?usp=sharing
> 
> It is miles better than your textual description in your original post.
> 
> Here is what you said initially:
> 
>> so I added an led through a resistor, a 10k pot and a LDR.  I then
>> connected the centre pin of the 10k pot to pin 2 on the top IC555
>> shown on the schematic
> 
> However, your new schematic above does *not* show the center pin of the
> 10k pot connected to pin 2 of the top 555.  It shows the center pin of
> the 10k pot connected to the positive voltage rail, and the positive
> voltage rail connected to pin 2 of the 555.  Note also that your
> annotations are wrong.  You have the line to pin 2 annotated as "to
> pin 3" and the wire to pin 3 annotated as "to pin 2".
> 
> So, either your textual description is wrong, or your new schematic
> drawing additions are wrong.  But you can't expect anyone here to be of
> much help when you provide incorrect information at the outset.
> 
Oops, apologies for the error in the previous schematic of added parts.
I have corrected it now:

> If you've built the circuit like you show in the new schematic, the top
> 555 will not do anything, because pin 2 is the trigger input, and you
> have it shown as strapped to the positive voltage rail.  So the upper
> 555 simply will not oscillate.
> 
> Also, your schematic shows no bypass capacitors for the 555's.  You've
> left out another critical bit of information.  Are you using bipolar
> 555's or CMOS 555's?  Because if you are using bipolar 555's, you'll
> very much want to add bypass cap's across the 555 power rails.

As I said in my OP I built the circuit from an article in a book I 
bought several months ago, and it doesn't say to use CMOS 555's or 
bipolar 555's, but just 555's.

https://drive.google.com/file/d/1O4LWsY41SLjjMaRgLAbh7kONCRkAx9LR/view?usp=sharing
> 
> Also, another tip, when positing schematic pictures here asking for
> help, it is best to add numbers to all the components (i.e., R1, R2,
> C1, C2, U1, U2, ...).  That helps you and us have a common nomenclature
> with which to refer to specific items on the schematics.
> 

I've named the added 320 ohm resistor as R1, and both the led and the 
10k pot centre pin is connected to pin 3 on the 555

https://drive.google.com/file/d/1OyIH7dWiGtX08ytolqDMsCqT-tQxg8nz/view?usp=sharing


Thanks

On 2020-11-24 21:35, RobH wrote:
> On 24/11/2020 16:43, Rich wrote:
>> RobH <rob@despammer.com> wrote:
>>> On 24/11/2020 08:41, Andy Burns wrote:
>>>> RobH wrote:
>>>>
>>>>> This is why I hate asking questions here. No help, just castigated.
>>>>
>>>> You're asking people to compare a schematic circuit diagram to a
>>>> breadboard built circuit, that's over the threshold most people are
>>>> willing to get into.
>>>>
>>>> Why not provide a similar schematic showing your alterations?
>>>>
>>>>
>>> Ok, I take your point.
>>>
>>> I have added the 10k pot, led and ldr onto the original schematic.
>>> It's the best I can do, I'm afraid, and hope it's clear enough.
>>>
>>> https://drive.google.com/file/d/1ObLBgJfce4fMPrvRTk5emIRcJzxhNWOt/view?usp=sharing
>>
>> It is miles better than your textual description in your original post.
>>
>> Here is what you said initially:
>>
>>> so I added an led through a resistor, a 10k pot and a LDR.  I then
>>> connected the centre pin of the 10k pot to pin 2 on the top IC555
>>> shown on the schematic
>>
>> However, your new schematic above does *not* show the center pin of the
>> 10k pot connected to pin 2 of the top 555.  It shows the center pin of
>> the 10k pot connected to the positive voltage rail, and the positive
>> voltage rail connected to pin 2 of the 555.  Note also that your
>> annotations are wrong.  You have the line to pin 2 annotated as "to
>> pin 3" and the wire to pin 3 annotated as "to pin 2".
>>
>> So, either your textual description is wrong, or your new schematic
>> drawing additions are wrong.  But you can't expect anyone here to be of
>> much help when you provide incorrect information at the outset.
>>
> Oops, apologies for the error in the previous schematic of added parts.
> I have corrected it now:
>
>> If you've built the circuit like you show in the new schematic, the top
>> 555 will not do anything, because pin 2 is the trigger input, and you
>> have it shown as strapped to the positive voltage rail.  So the upper
>> 555 simply will not oscillate.
>>
>> Also, your schematic shows no bypass capacitors for the 555's.  You've
>> left out another critical bit of information.  Are you using bipolar
>> 555's or CMOS 555's?  Because if you are using bipolar 555's, you'll
>> very much want to add bypass cap's across the 555 power rails.
>
> As I said in my OP I built the circuit from an article in a book I bought several months ago, and it doesn't say to use CMOS 555's or bipolar 555's, but just 555's.
>
> https://drive.google.com/file/d/1O4LWsY41SLjjMaRgLAbh7kONCRkAx9LR/view?usp=sharing
>>
>> Also, another tip, when positing schematic pictures here asking for
>> help, it is best to add numbers to all the components (i.e., R1, R2,
>> C1, C2, U1, U2, ...).  That helps you and us have a common nomenclature
>> with which to refer to specific items on the schematics.
>>
>
> I've named the added 320 ohm resistor as R1, and both the led and the 10k pot centre pin is connected to pin 3 on the 555
>
> https://drive.google.com/file/d/1OyIH7dWiGtX08ytolqDMsCqT-tQxg8nz/view?usp=sharing
>
>
> Thanks

You never actually stated what your modifications are supposed
to accomplish. Doesn't Platt explain how the 555 works? Doesn't
he explain how IC pins are numbered? Doesn't he explain how to
identify the connections on a potentiometer? Doesn't he explain
what LEDs are and how to use them? All of those are the things
you got wrong. There are probably more, hard to tell.

For an older electronics professional, it is sometimes good to
be reminded how many errors a beginner can make. I had your
problems fifty years ago. (No, I didn't have 555s then.)

Jeroen Belleman

In article <rpjvf8$1qpc$1@gioia.aioe.org>, jeroen@nospam.please says...
> 
> For an older electronics professional, it is sometimes good to
> be reminded how many errors a beginner can make. I had your
> problems fifty years ago. (No, I didn't have 555s then.)
> 
> Jeroen Belleman
> 
> 

Being invented in 1971 it is almost 50 years ago.

That is another cockroach that will not die.

RobH <rob@despammer.com> wrote:
> On 24/11/2020 16:43, Rich wrote:
>> However, your new schematic above does *not* show the center pin of 
>> the 10k pot connected to pin 2 of the top 555.  It shows the center 
>> pin of the 10k pot connected to the positive voltage rail, and the 
>> positive voltage rail connected to pin 2 of the 555.  Note also that 
>> your annotations are wrong.  You have the line to pin 2 annotated as 
>> "to pin 3" and the wire to pin 3 annotated as "to pin 2".
>> 
>> So, either your textual description is wrong, or your new schematic 
>> drawing additions are wrong.  But you can't expect anyone here to be 
>> of much help when you provide incorrect information at the outset.
>> 
> Oops, apologies for the error in the previous schematic of added parts.
> I have corrected it now:

Are you sure you have.  Your new schematic photo now shows a dead short 
between the positive and negative power rails, and does not show three 
pins on the 10k pot (so no center pin connected anywhere.

>> Also, your schematic shows no bypass capacitors for the 555's.  You've
>> left out another critical bit of information.  Are you using bipolar
>> 555's or CMOS 555's?  Because if you are using bipolar 555's, you'll
>> very much want to add bypass cap's across the 555 power rails.
> 
> As I said in my OP I built the circuit from an article in a book I 
> bought several months ago, and it doesn't say to use CMOS 555's or 
> bipolar 555's, but just 555's.

The question was quite clear, but perhaps you missed it, so I'll repeat 
it below:

> Are you using bipolar 555's or CMOS 555's?

> https://drive.google.com/file/d/1O4LWsY41SLjjMaRgLAbh7kONCRkAx9LR/view?usp=sharing
>> 
>> Also, another tip, when positing schematic pictures here asking for
>> help, it is best to add numbers to all the components (i.e., R1, R2,
>> C1, C2, U1, U2, ...).  That helps you and us have a common nomenclature
>> with which to refer to specific items on the schematics.
>> 
> 
> I've named the added 320 ohm resistor as R1, and both the led and the 
> 10k pot centre pin is connected to pin 3 on the 555
> 
> https://drive.google.com/file/d/1OyIH7dWiGtX08ytolqDMsCqT-tQxg8nz/view?usp=sharing

This schematic shows only two of three pins of the pot (presumably you 
have a three pin pot, as you did begin with "center pin of pot 
connected..."

But with the dead short in this version across the power rails (if the 
schematic matches how you have it wired), all you will achieve from 
this version is warming up your power supply (or blowing it up, 
depending on whether it tolerates a dead short).

On 11/24/20 4:54 PM, Jeroen Belleman wrote:

> 
> For an older electronics professional, it is sometimes good to
> be reminded how many errors a beginner can make. I had your
> problems fifty years ago. (No, I didn't have 555s then.)

And you had to make protons go round and round in mason jars. ;)

Cheers

Phil Hobbs

"In my day, we defragged hard disks by editing the inodes by hand.  With 
magnets"


-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

On 25/11/2020 04:42, Rich wrote:
> RobH <rob@despammer.com> wrote:
>> On 24/11/2020 16:43, Rich wrote:
>>> However, your new schematic above does *not* show the center pin of
>>> the 10k pot connected to pin 2 of the top 555.  It shows the center
>>> pin of the 10k pot connected to the positive voltage rail, and the
>>> positive voltage rail connected to pin 2 of the 555.  Note also that
>>> your annotations are wrong.  You have the line to pin 2 annotated as
>>> "to pin 3" and the wire to pin 3 annotated as "to pin 2".
>>>
>>> So, either your textual description is wrong, or your new schematic
>>> drawing additions are wrong.  But you can't expect anyone here to be
>>> of much help when you provide incorrect information at the outset.
>>>
>> Oops, apologies for the error in the previous schematic of added parts.
>> I have corrected it now:
> 
> Are you sure you have.  Your new schematic photo now shows a dead short
> between the positive and negative power rails, and does not show three
> pins on the 10k pot (so no center pin connected anywhere.
> 
>>> Also, your schematic shows no bypass capacitors for the 555's.  You've
>>> left out another critical bit of information.  Are you using bipolar
>>> 555's or CMOS 555's?  Because if you are using bipolar 555's, you'll
>>> very much want to add bypass cap's across the 555 power rails.
>>
>> As I said in my OP I built the circuit from an article in a book I
>> bought several months ago, and it doesn't say to use CMOS 555's or
>> bipolar 555's, but just 555's.
> 
> The question was quite clear, but perhaps you missed it, so I'll repeat
> it below:
> 
>> Are you using bipolar 555's or CMOS 555's?
> 
>> https://drive.google.com/file/d/1O4LWsY41SLjjMaRgLAbh7kONCRkAx9LR/view?usp=sharing
>>>
>>> Also, another tip, when positing schematic pictures here asking for
>>> help, it is best to add numbers to all the components (i.e., R1, R2,
>>> C1, C2, U1, U2, ...).  That helps you and us have a common nomenclature
>>> with which to refer to specific items on the schematics.
>>>
>>
>> I've named the added 320 ohm resistor as R1, and both the led and the
>> 10k pot centre pin is connected to pin 3 on the 555
>>
>> https://drive.google.com/file/d/1OyIH7dWiGtX08ytolqDMsCqT-tQxg8nz/view?usp=sharing
> 
> This schematic shows only two of three pins of the pot (presumably you
> have a three pin pot, as you did begin with "center pin of pot
> connected..."
> 
> But with the dead short in this version across the power rails (if the
> schematic matches how you have it wired), all you will achieve from
> this version is warming up your power supply (or blowing it up,
> depending on whether it tolerates a dead short).
> 

Is this any clearer:

https://drive.google.com/file/d/1PL_AeVMofix5-WLABwicplR49_bNAyrj/view?usp=sharing

If it's not then , I'll just forget about it, as it was only something I 
wanted to do while in lockdown.

I didn't miss your question about the 555's as I answered you:

As I said in my OP I built the circuit from an article in a book I 
bought several months ago, and it doesn't say to use CMOS 555's or 
bipolar 555's, but just 555's.

In case you missed my  OP, I already built the said circuit previously 
and have it working fine.

Thanks anyway

On 2020-11-25 09:10, Phil Hobbs wrote:
> On 11/24/20 4:54 PM, Jeroen Belleman wrote:
>
>>
>> For an older electronics professional, it is sometimes good to
>> be reminded how many errors a beginner can make. I had your
>> problems fifty years ago. (No, I didn't have 555s then.)
>
> And you had to make protons go round and round in mason jars. ;)
>
> Cheers
>
> Phil Hobbs
>
> "In my day, we defragged hard disks by editing the inodes by hand.  With magnets"
>
>

In those days, I had no idea that one could become a 'physicist'.
There were no engineers or academics in my environment, or my
choices might have been quite different. I discovered the very
existence of labs dedicated to physics research when I was 19
years old, quite accidentally as a side effect of my negligence
to secure a local position as a technical student. It turned out
to be a lucky strike. :-)

Jeroen Belleman

On 25/11/2020 09:40, Jeroen Belleman wrote:
> On 2020-11-25 09:10, Phil Hobbs wrote:
>> On 11/24/20 4:54 PM, Jeroen Belleman wrote:
>>
>>>
>>> For an older electronics professional, it is sometimes good to
>>> be reminded how many errors a beginner can make. I had your
>>> problems fifty years ago. (No, I didn't have 555s then.)
>>
>> And you had to make protons go round and round in mason jars. ;)
>>
>> Cheers
>>
>> Phil Hobbs
>>
>> "In my day, we defragged hard disks by editing the inodes by hand.  
>> With magnets"
>>
>>
> 
> In those days, I had no idea that one could become a 'physicist'.
> There were no engineers or academics in my environment, or my
> choices might have been quite different. I discovered the very
> existence of labs dedicated to physics research when I was 19
> years old, quite accidentally as a side effect of my negligence
> to secure a local position as a technical student. It turned out
> to be a lucky strike. :-)
> 
> Jeroen Belleman

Aah, well I was a mechanical engineer for over 40 years, and I can read 
drawings including schematics. I can't draw tho'.

On 2020-11-25 10:19, RobH wrote:
> On 25/11/2020 04:42, Rich wrote:
[...]

>>
>> The question was quite clear, but perhaps you missed it, so I'll
>> repeat it below:
>>
>>> Are you using bipolar 555's or CMOS 555's?
[...]
>
> Is this any clearer:
>
> https://drive.google.com/file/d/1PL_AeVMofix5-WLABwicplR49_bNAyrj/view?usp=sharing
>
>  If it's not then , I'll just forget about it, as it was only
> something I wanted to do while in lockdown.
>
> I didn't miss your question about the 555's as I answered you:
>
> As I said in my OP I built the circuit from an article in a book I
> bought several months ago, and it doesn't say to use CMOS 555's or
> bipolar 555's, but just 555's.
>
> In case you missed my  OP, I already built the said circuit
> previously and have it working fine.

This is becoming a 'dialogue de sourds'. The question was
"Are you using bipolar 555's or CMOS 555's?". You did *not*
answer that question. Just give us the exact type as read
from the actual DIP you have in there!

You still haven't explained what the intended effect of
the added components is. How are we to know what it is
*supposed* to do?

Your picture still leaves much to be desired, hiding several
crucial details. One thing is clear though: The potentiometer
will have little or no effect until it reaches either end.

If the LED lights at all, it will likely be full on or full
off with the potentiometer at either end, and perhaps blink
for intermediate settings. Even so, this abuses the 555, the
potentiometer and the 9V battery. You seem to be trying to
overpower the 555's output with the centre tap of the
potentiometer.

Jeroen Belleman