[555 calculation in astable mode]

yes absolutely but i have only time for on/off and haven't any parameters like resistors and capacitor for using formulas.
i think i should revers working. because when you have resistors and capacitor you can use 555 calculator for result.
and result are space and mark time

[555 calculation in astable mode]

Hello dear friend
could you help me for designing a LED blinker with  two properties:
5 seconds LED on and 2 seconds LED off and repeat.
how can i calculate space time and mark time for these R1 , R2, C1 for making 5 and 2 seconds?

[circuit isolation]

hi
i have problem with my micro controller (PIC)  board for control of camera (turn left and right). in this circuit used 7805 for making 5voltage for all component of circuit and camera (cctv work with 5v). but when turning on this circuit , av receiver can't  receive signal from camera. but when i disconnected this camera from circuit and plug in to different 5v power supply work very well and i have good signal in AV receiver.

i guess problem is in power supply (maybe noise ).

have you any idea for this circuit that work with one 9-12v adapter in input voltage but have two apart 5v in circuit?
that i use micro controller board and camera separately.
thanks

[lm7805 question]

can you tell me more about this statement about these values

"The value isn't critical but if you make it too small you risk it being inadequate to damp oscillation. If you make it too big, at least with a single capacitor, you run the risk of the high frequency impedance of the capacitor being too high.  "

damp oscillation and high frequency impedance  ?

thanks

[lm7805 question]

what is the different between c1 and c2 will be 100uf instead of 10uf?

[lm7805 question]

hi friends
please see this attachment.
can you tell me why use c1 and c2 for lm7805 and why in other config we use capacitors with different values.
this pictures use for pic micro controller and LCD power supply.
thanks

[2n2222 resistor value]

thanks hero999
is there any formula for this issue?
my coil is 57ohm

[2n2222 resistor value]

hi friends
please show me how can i calculate resistor value  connected to base of 2n2222?
thanks

[temp. sensor ds1820]

hi
can anyone know about ds1820 and how can i work for getting temperature from ds1820? any calculation need?
i want to use pic micro controller and i just know more about ds1820
thanks

[change gas sensor sensitivity]

hi
if you read this post you will see i said MQ4(gas sensor)
and i want to know can i use potentiometer after output of this sensor for change sensitivity?
thanks

[change gas sensor sensitivity]

hi friends
please see this attachment.
can i use potentiometer for change MQ4 sensitivity before transistor ?

[Amplifier for ISD module]

hello friends
can you suggest me a simple amplifier for amplify output of ISD1420?
i need to hear the voice in the house only but i need good quality.
i think 1w or 0.5w is good.
thamks

[data transmmition with laser pointer]

i have laser pointer (use in presentation) and i want to transmit data up to 1meter (zero and one logical method ) , with receiver sensor. for first in this issue i need circuit for amplify signal (fast switching) in receiver. look at this schematic !!
i know how can i make signal in transmitter with micro controller but i have problem with using 2pin receiver sensor.
if you have any idea for amplify signal in receiver circuit? 

[data transmmition with laser pointer]

hi friends
have you any idea for sending data (0 or 1) with laser diode to receiver diode with PIC micro controller and indicate to LCD 2*16 characterize lcd??
thanks

[design with DAC0808]

hello friends
i have question
can we make a dc motor driver like 4bit  step motor with DAC808?
can you suggest a circuit?
thanks

[please fined DAC0804]

hi dears friends
i want to fined dac0804 but i cant it digital to analog 8 bit. i fined a site but not work.
http://www.ic2ic.com/search.jsp?sSearchWord=DAC0804&q=DAC0804
thanks

[Stepper motor control]

hi friends
can you help me for driving this motor?
i have motor driver work with microcontroller. i want to drive 4 wire stepper motor "AIRPAX".
thanks

[Window Car circuit]

hi
no my friend i want to make circuit for amplifier for better driving motor.

[Window Car circuit]

hi friends
can you help me how can i make window car circuit for more speed?
thanks

[Diode]

hi friends
can you help me about these diodes i have only diodes but i dont know about these.
thanks

[c828 transistor]

thanks friends
can you tell me is a equalizer circuit can be amplifier circuit?
i have circuit that have very low output i dont know why

[c828 transistor]

hi friend
i have audio amplifier made with 2 * C828.
can you tell me which transistor use instead c828?
thanks

[direct connect dvd or cd ROM to TV]

hi
have you any idea for connecting dvd or cd ROM to tv without PC?
SATA will be complicated but how about IDE cable ?
have you any interface circuit ?
thanx ;)

[high precise Temperature sensor]

i need to fined new strong sensor.

[high precise Temperature sensor]

Hello friends
my expert friends I hope you have good day . in some months ago i made a project for sensing ambient  temperature with PIC micro controller and sensor was DS1820 and show at  2*16 character LCD.
you can see scheme in this attachments.

but i now looking for high precise temperature sensor that can sense in thousandth degree in centigrade.

can you introduce me a high precise temperature sensor?? or you think  i should use DS1820 but change program?
thanks