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High Logic time
I'm using the uC 89C51 in a monitoring purpose.
The uC will be counting the number of pulses on a certain pin of a port for a fixed period of time.When the number of incoming pulses in that period of time exceeds a particular number 'X', the uC has to sound an alarm.
What should...
Voltage converter query
I have a system which gives an o/p :
1> Rectangular wave of peak-to-peak voltage 4.6V, on-time approx. 600usec, off-time approx. 800usec. when a condition 'A' is met.
2> A DC voltage of 1.7 V when condition 'B' is met.
Can a circuit be designed where
1> The...
I've designed a monitoring transmitter-receiver system in which the o/p of the receiver is :
1> A rectangular wave of peak-to-peak voltage 4.6V, on-time 600usec, off-time 800usec when the transmitter signal is being received.
2> A DC voltage of 1.7V when the transmitter signal is absent.
How...
reed carrying current
I'm working on a project and need the current through a wire to be switched off and on at a fast rate.
The wire will be carrying a constant current of 25 - 50 mA.
I'll be using a dry reed relay for this switching purpose (Is there a better option?)
What i need to know is ...
i have a few queries :
1>Should i found out phone line current ? Is it safe to do so ? Current in this can be measured with a multimeter ?
2>How do i decide the reed relay rating ?
3> Is contact protection essential ?
Please help me regarding these doubts
I read the datasheet of Atmel uC AT89C51.(found here :
http://www.atmel.com/dyn/resources/prod_documents/doc0265.pdf )
According to the datasheet ( pg 10),
Min Max
VIL Input Low-voltage (Except...
1> Isn't the diode across the reed relay providing sufficient protection ?
If not, what should be the additional circuitry involved for over voltage protection ?
2> Also, i didn't understand the modem-transformer part properly.How is it generating a 300 Hz tone ? Does the pin 9 have an...
I want to enable pulse dialling in a project that uses a landline telephone and a microcontroller.
1>Should i use a dedicated IC ? Or will a relay switch do ?
2>If i use pulse dialling technique, which relay should i use? A reed relay?
3>How many lines are actually there in a telephone line...
pulse dialling
I want to enable pulse dialling in a project that uses a landline telephone and a microcontroller.
1>Should i use a dedicated IC ? Or will a relay switch do ?
2>If i use pulse dialling technique, which relay should i use? A reed relay?
3>How many lines are actually there in a...
tsop1738
Finally, i got the o/p of TSOP 1738.Just had to tinker about a bit with the pots connected to the 555's.
As "Audioguru" says, its o/p is high when no signal is detected, and low, when there's a 38kHz signal.
Thanx to "Audioguru".
hello everybody, i'm currently working on my final year project
this is the idea it is based on:
a circuit (transmitter) mounted on a door is made to send a pulsed IR beam across to a circuit (receiver) mounted on the wall adjacent to the door.
a microcontroller monitoring the receiver circuit...
ir receiver circuit using tsop
The TSOP 1738 datasheet states that the burst length should be 10 cycles/burst or longer, OR between 10 cycles and 70 cycles and a gap time of at least 14 cycles is necessary.
1 "cycle" here means inverse of 38kHz, right?
That works out to 26.32usec
40(average of...
working of tsop1738
what happens if the TSOP 1738 receives a signal that is continuously at 38kHz, i.e. a signal that is not pulsed, like in my first post?
Will the o/p of TSOP be continuosly high ?
tsop 1738 ir receiver
Can somebody please tell me how a call is placed using a landline phone, and what signal is sent back to the calling party when the called party has picked up the phone?
tsop1738 ir receiver
Also, when somebody picks up a landline telephone and dials a number, he knows when the called party has picked up the telephone.
Im using a microcontroller in the above circuit. Lets say the system is switched ON and an intruder breaks into the house. Using the process...
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