Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

I wish to make a 555 circuit myself?

Status
Not open for further replies.
greentree

greentree

Member level 5
Joined
Sep 25, 2011
Messages
86
Helped
13
Reputation
26
Reaction score
13
Trophy points
1,288
Location
The center of world!
Activity points
1,739
Hi every body*
At first i must say that i built the 555 circuit ... but it didn't work good!
RS flipflop worked but always R and S was high!?
I cann't understand what happened to it !

And i must say too that i built RS flipflop with two NAND gates . how can i make it with transistor.
 

You will have to show your circuit for anyone to help.

RS flipflop worked but always R and S was high!
Click to expand...
doesn't make sense. Check what you expect from the logic you have designed and see if it behaves correctly. I believe a simple RS flip-flop using NAND gates produces inverted outputs and the inputs are inverted as well, but I am not sure.

It is possible that the 555 circuit you are using shows an RS flip-flip with input & output logic different to yours and you will need some inverters to correct the logic.

Keith.
 

Hi
555.JPG
the out always is high !?

best wishes
Green tree
 

You should have a resistor in Q1 base.

Try connecting Q1 base through a resistor to OUT not U4.

Keith.
 
oops!:oops:
Yes you're right.
I forget it . thank you , i put it an say you its result...

Best wishes
Green tree
 

Don't forget to move the connection to OUT as well. If you follow the logic through it will get stuck with the output high with the logic you have (which is what is happening). You need it so when OUT goes high it starts the discharge.

Keith.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top