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Amateur alarm circuit problem

Started by RobH November 22, 2020
I built an alarm circuit from a book I bought called Make Electronics by 
Charles Platt.

https://drive.google.com/file/d/1NxvKdZCqykuSjBvPVoWz_MEMhKYMMz9E/view?usp=sharing

The said circuit produces a siren type sound on a buzzer  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


Working  version of the circuit
https://drive.google.com/file/d/1NwYnNkljKLd7ORmZ16VYrtb7ZwCsvAn_/view?usp=sharing

As the said circuit was working as I wanted with the ldr and buzzer, I 
built another of the same circuit.

On this 2nd circuit, the led goes off when I adjust the 10k pot, but the 
sound does not. It does on the first circuit I built.

Thanks
On 22/11/2020 13:05, RobH wrote:
> I built an alarm circuit from a book I bought called Make Electronics by > Charles Platt. > > https://drive.google.com/file/d/1NxvKdZCqykuSjBvPVoWz_MEMhKYMMz9E/view?usp=sharing > > > The said circuit produces a siren type sound on a buzzer  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 > > > Working  version of the circuit > https://drive.google.com/file/d/1NwYnNkljKLd7ORmZ16VYrtb7ZwCsvAn_/view?usp=sharing > > > As the said circuit was working as I wanted with the ldr and buzzer, I > built another of the same circuit. > > On this 2nd circuit, the led goes off when I adjust the 10k pot, but the > sound does not. It does on the first circuit I built. > > Thanks
If anyone has replied to my post, I'm not seeing them.
On 2020-11-22, RobH <rob@despammer.com> wrote:
> I built an alarm circuit from a book I bought called Make Electronics by > Charles Platt. > > https://drive.google.com/file/d/1NxvKdZCqykuSjBvPVoWz_MEMhKYMMz9E/view?usp=sharing > > The said circuit produces a siren type sound on a buzzer 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 > > > Working version of the circuit > https://drive.google.com/file/d/1NwYnNkljKLd7ORmZ16VYrtb7ZwCsvAn_/view?usp=sharing > > As the said circuit was working as I wanted with the ldr and buzzer, I > built another of the same circuit. > > On this 2nd circuit, the led goes off when I adjust the 10k pot, but the > sound does not. It does on the first circuit I built. > > Thanks
With the 555 it's all about woltages, check that the voltages on the 555 inputs (pins 2,6,4, and 5) are what you expect them to be -- Jasen.
On Mon, 23 Nov 2020 20:13:49 +0000, RobH <rob@despammer.com> wrote as
underneath :

>On 22/11/2020 13:05, RobH wrote: >> I built an alarm circuit from a book I bought called Make Electronics by >> Charles Platt. >> >> https://drive.google.com/file/d/1NxvKdZCqykuSjBvPVoWz_MEMhKYMMz9E/view?usp=sharing >> >> >> The said circuit produces a siren type sound on a buzzer&#2013266080; 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 >> >> >> Working&#2013266080; version of the circuit >> https://drive.google.com/file/d/1NwYnNkljKLd7ORmZ16VYrtb7ZwCsvAn_/view?usp=sharing >> >> >> As the said circuit was working as I wanted with the ldr and buzzer, I >> built another of the same circuit. >> >> On this 2nd circuit, the led goes off when I adjust the 10k pot, but the >> sound does not. It does on the first circuit I built. >> >> Thanks > >If anyone has replied to my post, I'm not seeing them.
Not surprising - you have not made it easy to see exactly what you have done with the two circuits exactly as built side by side (not a breadboard picture). Why should anyone waste their time when you cannot be bothered yourself.
On Sun, 22 Nov 2020 13:05:12 +0000, RobH <rob@despammer.com> wrote:

>I built an alarm circuit from a book I bought called Make Electronics by >Charles Platt. >
Maybe you want to draw your circuit into Micro-Cap http://www.spectrum-soft.com/index.shtm It's easy. The run the simulation. That's how the professionals do it. No soldering anymore. At least you should draw the circuit as you modified it. I am not sure to understand your description. w.
>https://drive.google.com/file/d/1NxvKdZCqykuSjBvPVoWz_MEMhKYMMz9E/view?usp=sharing > >The said circuit produces a siren type sound on a buzzer 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 > > >Working version of the circuit >https://drive.google.com/file/d/1NwYnNkljKLd7ORmZ16VYrtb7ZwCsvAn_/view?usp=sharing > >As the said circuit was working as I wanted with the ldr and buzzer, I >built another of the same circuit. > >On this 2nd circuit, the led goes off when I adjust the 10k pot, but the >sound does not. It does on the first circuit I built. > >Thanks
On 24/11/2020 07:02, Charlie+ wrote:
> On Mon, 23 Nov 2020 20:13:49 +0000, RobH <rob@despammer.com> wrote as > underneath : > >> On 22/11/2020 13:05, RobH wrote: >>> I built an alarm circuit from a book I bought called Make Electronics by >>> Charles Platt. >>> >>> https://drive.google.com/file/d/1NxvKdZCqykuSjBvPVoWz_MEMhKYMMz9E/view?usp=sharing >>> >>> >>> The said circuit produces a siren type sound on a buzzer&nbsp; 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 >>> >>> >>> Working&nbsp; version of the circuit >>> https://drive.google.com/file/d/1NwYnNkljKLd7ORmZ16VYrtb7ZwCsvAn_/view?usp=sharing >>> >>> >>> As the said circuit was working as I wanted with the ldr and buzzer, I >>> built another of the same circuit. >>> >>> On this 2nd circuit, the led goes off when I adjust the 10k pot, but the >>> sound does not. It does on the first circuit I built. >>> >>> Thanks >> >> If anyone has replied to my post, I'm not seeing them. > > Not surprising - you have not made it easy to see exactly what you have > done with the two circuits exactly as built side by side (not a > breadboard picture). Why should anyone waste their time when you cannot > be bothered yourself. >
This is why I hate asking questions here. No help, just castigated.
On 24/11/2020 07:11, Helmut Wabnig wrote:
> On Sun, 22 Nov 2020 13:05:12 +0000, RobH <rob@despammer.com> wrote: > >> I built an alarm circuit from a book I bought called Make Electronics by >> Charles Platt. >> > > > Maybe you want to draw your circuit into Micro-Cap > http://www.spectrum-soft.com/index.shtm > > It's easy. The run the simulation. > That's how the professionals do it. No soldering anymore. > > At least you should draw the circuit as you modified it. > I am not sure to understand your description. > w. > > >
Thanks but there is nothing on that site for linux machines.
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?
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
On 24/11/2020 05:40, Jasen Betts wrote:
> On 2020-11-22, RobH <rob@despammer.com> wrote: >> I built an alarm circuit from a book I bought called Make Electronics by >> Charles Platt. >> >> https://drive.google.com/file/d/1NxvKdZCqykuSjBvPVoWz_MEMhKYMMz9E/view?usp=sharing >> >> The said circuit produces a siren type sound on a buzzer 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 >> >> >> Working version of the circuit >> https://drive.google.com/file/d/1NwYnNkljKLd7ORmZ16VYrtb7ZwCsvAn_/view?usp=sharing >> >> As the said circuit was working as I wanted with the ldr and buzzer, I >> built another of the same circuit. >> >> On this 2nd circuit, the led goes off when I adjust the 10k pot, but the >> sound does not. It does on the first circuit I built. >> >> Thanks > > > With the 555 it's all about woltages, check that the voltages on the > 555 inputs (pins 2,6,4, and 5) are what you expect them to be > >
I don't know what the voltages are supposed to be nor expected them to be, but here are my findings if they are any use; Pin 2 No Led nor pot 3v, with led on and pot connected , it fluctuates between 5v and 6.8v With the led turned off by the pot, 7v decreasing With the led on, turned on by the pot, between 5v and 6.8v Pin 4 No Led nor pot 9v, with led on and pot connected , 9v With the led turned off by the pot, 9v With the led on, turned on by the pot, 9v Pin 5 No Led nor pot, 5.9v with led on and pot connected , 5.9v With the led turned off by the pot, 5.9v With the led on, turned on by the pot, 5.9v Pin 6 No Led nor pot, 3v with led on and pot connected , between 5v and 6v With the led turned off by the pot, 5.5v With the led on, turned on by the pot, between 5.2v an 6.5v