@bluebird,

BMorse have proposed a feasible solution and a high tech one.

This is an alternative low tech way trying to ease the problem. It is suitable for other forum members who don't/can't have the ability to program a MCU to do the caller ID decoding.

You might consider a telephone answering machine driving some sort of circuit adapter to connect/disconnect your phone. During the day, a timer connects the incoming line to the phones and bypassing the answering machine. At night time, the answering machine is in circuit and handling all incoming calls. When someone call in at night, s/he will hear the following message:

"You have reached Bluebird instead of XXXX_ISP, you'll need to dial xxx-xxx-xxxx for XXXX_ISP. If you actually want to call Bluebird, hang up now then redial after exactly one minute."

The adapter circuit then connects all your phones to the line after 50 seconds, for a period of 30 seconds to allow others to call in. This way you can have your sleep and would not miss any important or emergency calls.

 

That would be an option. Add depending on how many ISP calls you are getting. If you are getting one every minute, then every other call will get through.

 

Hi Mr. Chung,

It is very nice to see you on this topic too. You always have useful suggestions. The situation isn't as bad as retched thinks. I get these calls only once every few nights now as the majority of the traffic is shifting to ADSL. But it is still annoying enough.

Mr. Chung, you are well aware of my lousy electronic skills, so you will have to be much more specific OR even suggest circuits for such a set up. It is beyond me, as you know. But I will always give it a go when I have the right schematics. I am a bit familiar with PIC microcontrollers, so if you have to include them in your schematics go ahead and do it. I have the PIC programmer too.
I hope you will come up with a practical suggestion and post it for everyone to see and use if so they wish.

Thanks a lot
Bluebird

 

I hope you will come up with a practical suggestion and post it for everyone to see and use if so they wish.

I have come up with the following. Comments invited.

You might want to consider buying a lottery ticket if two persons rang your number for that ISP within 60 seconds.

 

Hi eblc1388

Sounds good, but I will have to wait until you come up with a much more detailed proposal. It is still a bit hard to digest for me. I have lots of patience though.

Cheers,
Bluebird

 

Hi Bluebirdian,

The fun is to come up with a workable circuit by yourself and learn electronic in the process of experimenting. I'm sure it will be a challenge for you too.

The above scheme prevents user from making a call to outside as the phones are disconnected from line during the night.

The improved version below corrects this by feeding the house phones with a weak DC source to emulate the actual phone system voltage. When user picks up the phone, the Off-hook detector will sense this and trigger Timer T2 to re-connect the phone back to the incoming phone line.

You will need to look hard at the diagram and try to understand what it is trying to do, a piece at a time. You will get lots of assistance from other users here.

 

Hi eblc1388,
I have managed to put an opto, a couple of transistors, a diode and a few other components together and get a relay to latch when the telephone rings. Now somebody said earlier that if I put a 1000uF cap. across the ring signal it will be silenced. I have not done this bit using components but have simulated it but I don't seem to get the ring silenced. Any suggestions as how to silence the ring using the relay that is activated when the phone rings. I will think of using a microcontroller to specify the times that I want this mechanism to be on or off at a later stage. I am not bothering with sending messages over the line explaining this or that. The idea is that when the phone rings a relay will be activated which will somehow silence the ring before it actually has a chance to sound. Then later I will tell it to only do so during certain times by using a microcontroller.

Thanks
Bluebird

 

Now somebody said earlier that if I put a 1000uF cap. across the ring signal it will be silenced.

I believe its member "ifixit" who had said the above statement. I too has no idea how it can be done. You will need to ask him instead.

I have not done this bit using components but have simulated it but I don't seem to get the ring silenced.

What did you do to simulate this, without using a telephone line?

I will think of using a microcontroller to specify the times that I want this mechanism to be on or off at a later stage.

If you're going to use a microcontroller in the end, then you might as well let it do all aspects of the work, like detecting phone rings, setting hours of no disturb.. etc...

Since BMorse has also been working on the same project using a microcontroller, I'm sure you will be hearing from him soon.

 

@ Bluebirdiran:
I am still working on the circuit, I have just been so busy with other things lately.... I have the main circuit done for the phone detection and the DTMF decoder IC, I am just still trying to figure out what uc to use, I have quite a few in stock, and I guess a pic16f628A would work, but limits the available I/O's if I wanted to include other things such as an LCD display..... so I might go with the pic16F887 (another one I have on hand...) this uc will at least give me plenty of I/O's for future expansions.... I will try to post some of the circuit schematics on here tonight....

B. Morse

 

Hi BMorse,

Great stuff. I was sure that you were working on the project. But to keep me busy, I have been doing tentative things which is helping me a lot to understand electronics as Chung has also pointed out.

Anyway, I will be waiting eagerly to see some tangible results.

Cheers
Bluebird

 

Hi eblc1388,

Mission accomplished, well in a way. I have managed to suppress the damned telephone ring by using the circuit mentioned above and adding to it a relay which puts a 400uF cap. 220v across the Tip & Ring wires. By some luck I added a resistor in the input of the opto to control the current, then all of a sudden if anybody rings, his or her call will stop ringing after the first couple of rings and then the phone goes on an off hook state (I think). Meaning the poor guy doesn't really have to keep waiting and think that the call will be answered. Instead he will realize that something is wrong and will hang up without wasting his/her time too much. This of course will not allow emergency calls through either, but for that we will just have to wait and see what BMorse will come up with.
Temporarily, for the timing I am using a mechanical timer to switch the power supply on for the times of no disturbance. Having said all that, I am hoping BMorse will come up with something much more methodic.

PS. I had simulated the first part using simulation software.

Thanks to both
Bluebird

 

Hi BMorse,

How are you getting on. Pls. tell me in a few words how far you have got so far.

Thanks a lot,
Bluebird

 

Hi BMorse,

How are you getting on. Pls. tell me in a few words how far you have got so far.

Thanks a lot,
Bluebird

Well like I had said I have been busy with a lot of other things (I tend to overfill my plate once in a while ) but I have been trying to figure this whole thing out with having the phone "connected" to the line without disturbing the whole phone line connection, and still being able to just pick it up and dial out if necessary....

Here is what I have been tinkering with so far, I have not implemented a microcontroller yet, since most of this circuit can be tested without one....


The main thing I am working on now has to do with loading the line as if the phone was connected directly to it while on hook, (the OFF_HOOK, and PHONE_CONNECT part of the above circuit....

Basically what I intend on having the uc do is to monitor the incoming rings and keep them from "getting" to the phones at preset times.... and at any time someone picks up a handset in the house, the uc will automatically connect the phones back to the incoming Line, in case of emergencies, but also monitor for DTMF tones, I figured I could use the # key on the keypad to initiate a communication link between the user and the uc, so it can be reprogrammed or other functions can be activated using any phone in the house.... or from somewhere else via phone control.... I tend to over complicate things when I first come up with an idea and it takes me some time to "settle" down and start with the simple basics first....

I was going to tinker with it some more this weekend, but so far I have not had any free time, right now I just had a few minutes to post a reply as to not keep you waiting, while I wait for some tattoo customers.... these should be quick and simple so I may have time yet today!!


B. Morse

 

Hello BMorse,

It looks good. I am definitely enjoying the challenge, I hope you are too. Wishing you all the success.

Bluebird

 

Hello BMorse,

It looks good. I am definitely enjoying the challenge, I hope you are too. Wishing you all the success.

Bluebird

Well, finally had a few minutes to spend working on this project..... I had some initial issues with the DTMF decoder IC circuit, then it dawned on me that I had DSL, so I slapped in a filter and got it to work, well to a certain extent, I had run into an issue that has me puzzled.... I can get the decoder IC to decode all the keypad digits, except for 4,5, 6 & 0 , for some reason I can not get it to decode or even respond to those keys, so I am gonna have to get some other value caps and various resistors from the shop tomorrow and try again.

B. Morse

 

I did some more reading on the datasheet for the HT9172, and it seems that all the keys I am having problems with are the ones with a low Frequency of 770..... for some reason my circuit is filtering these out, even though I used the typical application circuit in the datasheet of the device ....

B. Morse

 

A telephone line is supposed to be perfectly balanced. Your circuit is unbalanced.

 

Yes I kind of figured that may be the issue, so when I get home I am going to add this to the interface and see if I can get better results, plus the cheap DSL filter AT&T provides is still letting a lot of "noise" through so I am also going to change that....



B. Morse

 

Your 47uf capacitor is a dead short at DTMF frequencies so the tones will be severely muffled. The 0.1uF capacitor feeding the 4.7k resistor through the transformer cuts frequencies below 340 Hz which are not DTMF tones.

 

Your 47uf capacitor is a dead short at DTMF frequencies so the tones will be severely muffled. The 0.1uF capacitor feeding the 4.7k resistor through the transformer cuts frequencies below 340 Hz which are not DTMF tones.

Thanks for the heads up, I have not tested this circuit yet, the 47uF cap is supposed to be a shunt cap.... but most likely won't need it anyway....

B. Morse