Newb Student needs help with class proj. PLEASE HELP

[zemloh]

diffrence between the 2n6400 and the 2n6400g

Ok I am a newb in all this circuitry lingo so help me out. My prof. each gave us a cell phone in which he instructed us to be able to call the phone and be able to start a 7-12v motor. ( I know crazy project. ) well I removed the speaker and checked the output voltage with my multimeter and i'm only getting 00.6 mv from the speaker phone leads now my idea is to hook up a thyristor from the leads the spec. thyristor is model# 2N6400G just follow link

ON SEMICONDUCTOR|2N6400G|SCR Thyristor | Newark Canada

heres the pdf link on the specs:
https://www.onsemi.com/pub_link/Collateral/2N6400-D.PDF

Is .6 mv's enough to open the gate to power the 9v battery I have connected on the anode or cathode ( which one I dont know. I have no clue how to hook up a thyristor in the first place.) My question is...is their an easier way to do this? Is a thyristor a good choice? I need the gate to open letting the 9v send constant current to the motor,. Btw I am using a diffrent power supply, the idea is to have the phone ring sending .6mv's to the thyristors gate which will open the gate and let the 9v battery send power through. does this sound about right? If you look at the specs of the thyristor (pdf.) where am I hooking up the particular wires? The positive output from the phones speaker should be connected to the gate, and where do I connect the neg from the speaker output?? and the 9v battery's positive is hooked to the anode and the neg to the cathode, or vice versa??!! I guess what im getting at is how the hell do I hook this thing up the way I need it. Im running out of time on this project and I need major help! so pllllleeeeasse any suggestions? thoughts? Concerns? The specs on the thyristor is in pdf. form in the link I posted please help tell me what my minimum volts I need to open the gate! Thanks guys

 

[betwixt]

The 0.6mV is probably just residual voltage from the audio amplifier. It should be much more than that when the phone is ringing or there wouldn't be enough to produce the ringing tone.

However, there is probably an easier way. If all it has to do is ring and start the motor, try to find the voltage that turns the phones display backlight on. All phones illuminate their display (and sometimes keypad) when a call is received and that will be several volts DC which is much easier to work with and plenty to trigger your SCR.

If you are going to control the motor by responding to commands sent over the phone rather than just the ringing, the problem is a little more complicated but still very doable. You need to recognize keypad tones and act on which was sent.

Brian.

 

[zemloh]

well we have to use the current from the speaker to start the motor. Which means Im getting between .8mv and 1.0v tops. Im just wondering how to hook up the thyristor..Does my positive output from the speaker go to the gate? and my negative goes to??? and the 9v battery positive goes to the anode or cathode? and where does my positive output of 9v +- 1v go from the thyristor. I need someone with some experience in thyristors and whats the input and out put and where do my neg lines go?maybe I just hook the neg from my phone to the neg on my 9v battery output and attach my positive output from the phone to the gate. ( Which when sent .8 to 1. volt should open the gate ) Then hook the positive output from the 9v to the anode?or cathode? Then for the output to the motor it should come from the anode or cathode? Im confused on anode and cathode and what goes where? Am i even making sense anymore???:idea:

 

[Audioguru]

You need to ask your teacher to explain how a thyristor works.
Then ask your teacher to explain the AC voltage at the speaker of the cell phone.

 

[zemloh]

thats all part of the assignment, picking the cheapest most effective way to start the motor. So far im not getting much help, hopefully someone who knows how to hook up a thyristor gets involved in this thread...thx anyways man...

 

[AVM_NOIDA]

I would have tried this way. Thyristors in all practicle circuits are fired by pulse transformers. These are high frequency (ferrite core) transformers (in this case we need only one sharp pulse) Which generate a significantly high voltage pulse at the thristor gate. In size these are around a inch in width and depth and very easy to find.
The primary of PT is conneted in series with ringer (speaker or whatever it is).
The secondary is connected to the thyristor. You need to insert a switch in series with motor to off the thyristor.

Thanks and all the best.

Added after 3 minutes:

I would have tried this way. Thyristors in all practicle circuits are fired by pulse transformers. These are high frequency (ferrite core) transformers (in this case we need only one sharp pulse) Which generate a significantly high voltage pulse at the thristor gate. In size these are around a inch in width and depth and very easy to find.
The primary of PT is conneted in series with ringer (speaker or whatever it is).
The secondary is connected to the thyristor. You need to insert a switch in series with motor to off the thyristor.

Thanks and all the best.

 

[Audioguru]

So far im not getting much help, hopefully someone who knows how to hook up a thyristor gets involved in this thread.

Doesn't your teacher teach you anything about electronics?

 

[zemloh]

So far im not getting much help, hopefully someone who knows how to hook up a thyristor gets involved in this thread.

Doesn't your teacher teach you anything about electronics?

First off I just started the class, and I believe the reason he chose this assignment was to see what exactly we know about electronics, but thanks.....

 

[chand1]

Hi,
Do not blame the Professor. It is a very good project.
He wants a project like:
send SMS (from your Mobile) to a GSM module.
GSM module connected to a Microcontroller.
The Microcontroller decodes the message, and drives the DC motor at a particular speed. Speed depends on the code in the SMS.
You have to use PWM method to drive motor.

This is one method.

Good luck.