Comments Solicited

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Jim,

Are the pair of RT nodes always connected together (same for TR?), or are they through relay contacts?

A couple notes:

If you're trying to show the CO side of things, it's a little more complicated. First, the + side of the CO battery is connected to Earth, but that doesn't really matter in your application. There will be high voltage ringing when you get an incoming call. The TIP side of the line will stay near Earth when this happens, but the 86V@20Hz sinusoid will be superimposed on the -52V RING side. An ac-couple load, TIP to RING, of about 8Kohms is what a typical old style ringer looks like. When the subscriber goes "offhook" to answer the incoming call, the dc current that flows will be much larger because a phone "looks like" about 200ohms (at DC), so even if you have 1Kohm loop resistance, the net DC offhook load can be distinguished from the ringer load and so the line will be declared offhook (i.e., answered).

Perhaps you should explain what you're trying to accomplish with this circuit.

Bob

They're connected all the time. Shown that way to distinguish circuit from Spice test "fixture".

Open circuit line voltage measures 50VDC, short-circuit current measures 50mA.

Closure of relay will occur between rings. This will be the only "answer" circuit. (Ring detect circuitry, based on hcpl3700, not shown.)

Circuit "answers" and superimposes 2200Hz tone to make caller think they reached a modem.

Only 800, 866, 877 and 888 numbers will activate this circuit :-) ...Jim Thompson

I see that the "DISCHARGE" isn't being used in the timer ? I can only assume that the attenuation pulse that is taking place at the drain of the fet is enough to produce the (-) trigger to restart the timer again? Or did we make a mistake and tie the "Discharge" to common? The reason I ask is, you have a Si diode there and I can only see ~ 0.7 volts of ripple at that location? Is that enough to cover a 1/3 supply window for C2 to activation the "Trigger" when "Threshold" is reached?

Jamie

Jim Thompson wrote in news: snipped-for-privacy@4ax.com:

have you ever looked at the Telezapper? It briefly emits a tone that causes (older)automated systems to log the number as a null.

Naaaah! You know me, only elegant will satisfy ;-) My system blanks first ring, yet, unlike off-the-shelf, displays CID on each phone in the house. If caller is 800/866/877/888, no ringing at all in the house. At 4th sensed ring, switch in noise maker, hang up after 5 seconds of noise. I decided on modem answer tone since it's simplest to implement.

Known good guys ring right thru ;-) ...Jim Thompson

=A0 =A0 ...Jim Thompson

.7

It's another standard 555 astable configuration with OUT driving TRIG|| THRESH tied together. Phone line signals are current driven, not voltage, so the 555 is modulating the CO current by ~0.7/10=3D70mA pulses when it bypasses the 10R in parallel with the 2N7000.

Hmm.

I don't have Jim's LMC555 model so I used a monolithic model and his circuit. It does exactly what I would expect it to do. It does not work. It only gives the first initial pulse at initial power and when C2 reaches the 2/3 levels, shuts off the output which then turns off the mosfet how ever, that is where it stops, C2 is charged now and the trigger isn't getting restarted?

When M1 is off, you get the expected 0.7V pulse increase at the trigger/threshold input due to the level shift on the other side of C2

You got me ? maybe the cmos version behaves differently?

If I connect the discharge line to the trigger and threshold, it works perfectly.

Must be one of those easter eggs I don't understand. Jamie

=A0 =A0 =A0...Jim Thompson

is

orks

Pin 2 and 6 are connected to the output pin 3 through resistor R2. You get a square wave. Pin 7 is not needed.

-Bill

Jim Thompson wrote in news: snipped-for-privacy@4ax.com:

I also recall a device that answers the phone silently,plays a recorded message,and asks the caller to input a 4 digit number to ring the resident. Otherwise,it just hangs up.

For your design,too bad it can't be 5 sec of extremely LOUD,deafening noise. B-)

death to telemarketers! By "Boomba"! (a joke I won't repeat in public.)

BTW,did you hear about Charlie Sheen doing cocaine? He took enough to kill two and a half men! :-P

Charlie Sheen is just dimboob on Cocaine! WHINNING!!!

Can't be. At least Sheen is familiar with women, AlwaysWrong only knows Rosy Palm.

Charlie has a couple hundred million... minimum.

Do you?

Dimboob was his stillborn twin

Numer0 Un0 wrote in news: snipped-for-privacy@4ax.com:

Maybe tied up in real estate and a large part alloted to former wives alimony and child support. I note he's changing his tune and trying to get his LUCRATIVE job back.

ZOOM,right over your head. ....it was a JOKE I heard....

snipped-for-privacy@4ax.com:

at least he's having some fun wasting his money :), not like those who lose it all trying to get even richer on stocks giving it Madoff and his likes

"I spent a lot of money on booze, birds and fast cars. The rest I just squandered."

-George Best

-Lasse

You know what? I stand corrected. For what ever reason, I didn't notice R2 being connected to the output. I sim that and put R2 from VCC.. I must be getting old...Yes, that would work perfectly.. ;)

Thanks for the heads up

Jamie

What if they call using a hidden number?

Hidden/unknown is also handled the same way. ...Jim Thompson

Nope. You are thinking of other idiots, Like Michael Jackson, before he croaked.

Charlie has managed his money a lot better than you think, pal.

Are you sure that's what his words were meant to do?

Nothing has gone over my head. Sorry to disappoint you.