Home Community

Recent Posts
Welcome, Guest. Please login or register.
April 23, 2014, 01:53:56 AM
Home Help Search Calendar Login Register
News: trade your components on this new board: "Components trade"

Advertisements
No New Posts
Today at 01:39:33 AM
in
Advertisements
by google

+  Electronics-Lab.com Community
|-+  Recent Posts
Pages: [1] 2 3 ... 10

 1 
 on: April 22, 2014, 01:13:46 PM 
Started by Big zee - Last post by Hero999
I agree with the above: you should test the 555 timer circuit first to be sure it works on its own.

If the relay is already being driven from a transistor, there's no need for a diode.

Have you connected the 0V rails of both circuits together? There needs to be a common 0V reference for the circuits to interface with one another.

If a pulse is applied to pin 2 for longer than the length of the delay, the output will stay high until the input goes low again. If this is a problem, you should AC couple pin 2 to the trigger signal via a small capacitor (100pF to 100nF) and bias it to +V with a pull-up resistor (10k to 1M).

See the application note linked below for more information:
http://www.doctronics.co.uk/pdf_files/555an.pdf

 2 
 on: April 22, 2014, 07:49:35 AM 
Started by Big zee - Last post by redwire
why don't you  connect a resistor and led to the output (pin 3) of the 555 first. You can visually see what's going on.  Then work in the relay.

 3 
 on: April 22, 2014, 05:15:58 AM 
Started by Big zee - Last post by Big zee
no i didnít use a diode !
and the relay already got a transistor and its open and closes without even a signal (this is 1st problem)!!!!
the second one is when i press the remote it wonít open .. but in some case when its open by its self and i press the remote it will still open until i remove my finger .... and all my parts is new.
should i use a diode from pin 3 (output) to GND ?
thx.

 4 
 on: April 22, 2014, 04:48:37 AM 
Started by Big zee - Last post by Hero999
Did you use a back-EMF protection diode?

How much current does the relay take? You may need to add a transistor to drive the relay.

 5 
 on: April 22, 2014, 03:48:03 AM 
Started by dani9678 - Last post by hetztronics
 HELLO THERE MY SUGGESTION IS CHECK/CHANGE THE INVERTER BOARD THAT IS MOST LIKELY GET DAMAGED

 6 
 on: April 22, 2014, 03:38:39 AM 
Started by KevinIV - Last post by Hero999
Your circuit uses more components and is inferior.

It doesn't have to have a gain of 1. It's possible to use a higher gain.

See the circuit attached which has a gain of 10, enabling a more accurate 2.5V reference to be used, rather than a zener diode. It also has current limiting and a capacitor is connected to the output to improve the transient response.

 7 
 on: April 22, 2014, 02:31:28 AM 
Started by Big zee - Last post by Big zee
thanks a lot.
i got one last question...
pin 2 on the 555 the trigger can i connect the signal to it ?
when i use my project i connected the RF receiver to the relay with a single wire to open it but when i tried to connect that wire to pin 2 and the out (pin 3) to the relay it didnt work properly! do i have to ground something ?

 8 
 on: April 21, 2014, 08:49:42 PM 
Started by KevinIV - Last post by KevinIV
I know that circuit. The gain must be at least be 1. This circuit has a gain of 6 which has an obsolete voltage divider. Unless you want to get rid of something else.

 9 
 on: April 21, 2014, 08:31:08 PM 
Started by KevinIV - Last post by audioguru
Yes the circuit can be done. The problem is the gain has to be at least one. But not more.
There is no problem with our fixed circuit. The output of the circuit is connected directly to the inverting input of the opamp so the output of the circuit has a voltage exactly the same as the voltage at the non-inverting input of the opamp. Then the gain is exactly 1.

 10 
 on: April 21, 2014, 08:17:36 PM 
Started by KevinIV - Last post by KevinIV
Yes the circuit can be done. The problem is the gain has to be at least one. But not more.

Pages: [1] 2 3 ... 10

Advertisements
No New Posts
Today at 01:39:33 AM
in
Advertisements
by google


Login with username, password and session length

Powered by MySQL Powered by PHP Powered by SMF 1.1.19 | SMF © 2013, Simple Machines Valid XHTML 1.0! Valid CSS!

 

 

Search Site | Advertising | Contact Us
Elektrotekno.com | Free Schematics Search Engine | Electronic Kits