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measuring telephone line impedance
how can i measure long distance cooper Line impedance ?
i will measure the empedance of a telephone line which is cooper (0.9mm) and it is long distance 1km ~ 6 km .
there will be no any telephone signals, the 2 wires are reserved for this meauserement.
i...
BUILD a PCB
custom building or what ?
it is hard to build double side PCB, but it is possible.
but i think double side custom PCB is nothing without plated holes.
plated holes are very important for a double sided PCB
Cell Jammer
i dont know this issue but i think the theory is, generating a strong ,dominant signal in same frequency spectrum. so the cell phone frequencies can be suppressed. is it right?
edit:
Re: BUILD a PCB
hello,
there are 2 good photoessays ,
http://www.tonepad.com/photoessay.asp?photoEssayID=10&sequenceNo=1
http://www.tonepad.com/photoessay.asp?photoEssayID=11&sequenceNo=1
- make the footprint pads as big as possible,
- make holes in pads for drill easily
- you can work...
psoc 2002
this topic was created in 2002,
now in 2006,still, there is no any working custom psoc programmers.
there are some available but not stable.
if there is any custom programmer, please share,
thank you.
zxfeng:
thank you it works, i changed "stretch", CTRL+ALT+Y to CTRL+Y.
i use pads sp2.
nagaup3:
thank you, but i tried lots of time but it doesnt work.
i record the macro, to change mils to metric.
when i record it, i open the preferences, i change the unit, and close the window. and i stop the...
pads pcb macro
hello,
shortcut keys cant modified in PADS.
i tried to set a macro but it doesnt work.
for example, i want to switch in mils and metric with a shortcut. or etc.
is there anyone can set and modify macros code?
thank you
yoke+circuit
some PCB manufacturers firstly examine the CAMs of the PCB,
if there is something wrong or exceeds their manufacturing ability, they warn you,
for example, if a TSOP footprint's pads to close , they warn you and they changes pads , they make them thinner.
after the manucturing...
Hello,
i search but cant find what i want.
my circuit works with 12V and draws 0.18 A. and i want to use an ordinary 12V voltage adapter/regulator,
i want to protect my circuit from high voltage (>15V) and high current (>0.25A)
what can i use for this ? an IC or a protection circuit with...
hello,
how can we pulse the transistor?
can we use 555 ?
if 555 works wrong and gives always "HIGH ", transistors will be turn on and of course all IR leds will be burn.
do you have any idea, what kind of circuit , or what kind of 555 circuit can we use for this protection?
thank you.
hello ,
VCC = 12 V
Forward voltage of LED is 1.4V
it is a good idea to drive LEDs with 100 Hz.
in the data sheet, it says 100Hz %1 duty cycle to drive LEDs with 100mA ~ 1 A
its OK to use 555 to get that pulse signals?
thank you.
hello
i have 2.4GHz Video PAL & audio RF modules 16 dB. RX and TX.
need 5V.
how can i supply it?
is it necessary to feed them with a linear supply ? 7805 heats so much.
can we supply it with a switching power supply? (and which is recommended )
thank you.
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