How to merge these two circuits?

Thread Starter

rigerman

Joined Apr 25, 2014
40
Hi,

I have 2 circuits that I need to merge. I am not much of an electronics person so seeking help.



On the left is a transistor switching circuit. (Circuit 1) If +ve is applied to bases of T1 and T2, one of the transistors conduct and other transistor becomes dead.

On the right is a simple SN7400 based logic circuit where, Using 2 push button switches, one can control the LEDs Red and Green. That is
When circuit on - Green is On.
When Push Button 1 is pushed - Green Off, Red On
When Push Button 2 is pused - Green On, Green Off.

Additional Requirement:
Power to Circuit 2 off - Red On
My requirement is to power the Red LED constant when there is no voltage in Circuit 2 via a secondary power supply like a battery backup.

When power restores to circuit 2, the secondary power source will be cut off automatically.

Can this be accomplished by merging the above two circuits above?

Thanks in advance.

Rig
 
Last edited:

GopherT

Joined Nov 23, 2012
8,012
The right circuit only makes your circuit difficult. The right circuit will not switch LEDs if the previous button is not released before pressing the second switch. Your transistor circuit (left side) would need to be coupled to the flip flop circuit with capacitors and pull-up resistors.

An easier version, assuming there is either power or no power to the base of the left transistor.
image.jpg
 

Dodgydave

Joined Jun 22, 2012
8,688
Your flipflop is drawn wrong, and you could use a transistor to detect power failure, are both supplies the same voltage?
 

Thread Starter

rigerman

Joined Apr 25, 2014
40
Both circuits can have same voltage.

@GopherT - Thanks and Is this a better version of the left circuit?

The switches are Push to On. So everytime I push the switch the flip flop sets or resets.
 

AnalogKid

Joined Aug 1, 2013
8,259
For circuit 2, you don't say which power rail you are switching, but lets assume it is the +5V. If this is removed from the chip (pin 14) while the input pullup resistors still are powered, then the chip has voltage on its input pins but not its power pin. This is not a valid operating condition, and the chip might fail.

ak
 

GopherT

Joined Nov 23, 2012
8,012
Both circuits can have same voltage.

@GopherT - Thanks and Is this a better version of the left circuit?

The switches are Push to On. So everytime I push the switch the flip flop sets or resets.

I assumed you wanted transistors to replace the switches in the RIGHT circuit (Flip flop). The red/green LEDs can be powered (one at a time) with just transistors. No need for hte flip flop circuit and switches if that is the case. I am not sure (exactly) what you want. Please clarify.

Note that, as Analog Kid mentioned above, a chip like a NAND gate, should not have power to the pins.

Do you need the switches?
 

Fmrx

Joined Jan 28, 2015
28
What the man is asking ,how do you merge two circuits to join together .dont copy n paste what is said already on google ideas. there all plain and wrong and it's a constant repeating error . Ok first of I have to say you have two circuits for controlling switch .as to how you do your joking of the two circuits, is your own way of getting it to switch .you have a transitor with a base emitter collector .collector attaches to the other leg on the other board .then for the emitter attaches to your earth side .again it's all about how you made it .like for instants say I had a audio stage ,I would then need an amp stage. again this is two circuits needing joined together so collector and emitter attach to that amplifier stage so emitter and collector are the main pass through ,then if say I wanted to add another stage to make it 3 in 1 joined .i would repeat what I have already done.thats what you would do one leg to emitter one leg to collector and so on ,think of emitter is your earth think of collector is your positive side .
 
Last edited:

tracecom

Joined Apr 16, 2010
3,944
What the man is asking how do you merge two circuits to join together .dont copy n paste what is said already on google ideas there all plain and wrong and it's a constant repeating error . Ok first of I have to say you have two circuits for controlling switch .as to how you do your joking of the two circuits is your own way of getting it to switch .you have a transitor with a base emitter collector .collector attaches to the other leg on the other board .then for the emitter attaches to your earth side .again it's all about how you made it .like for instants say I had a audio stage I would then need an amp stage again this is two circuits needing joined together so collector and emitter attach to that amplifier stage so emitter and collector are the main pass through then if say I wanted to add another stage to make it 3 in 1 joined .i would repeat what I have already done.thats what you would do one leg to emitter one leg to collector and so on think of emitter is your earth think of collector is your positive side .
Capital letters, paragraphs, punctuation, and proofreading might make this understandable.
 

Fmrx

Joined Jan 28, 2015
28
Why would you need capital letters it's a plain and simple read it .im no sitting here putting a capital letter on each bloody sentence I do .if you don't like it then sorry don't read it at all .if I can read it and so can you .
 

tracecom

Joined Apr 16, 2010
3,944
Why would you need capital letters it's a plain and simple read it .im no sitting here putting a capital letter on each bloody sentence I do .if you don't like it then sorry don't read it at all .if I can read it and so can you .
I didn't say I couldn't read it. I implied that it made no sense.
 

djsfantasi

Joined Apr 11, 2010
5,968
Why would you need capital letters it's a plain and simple read it .im no sitting here putting a capital letter on each bloody sentence I do .if you don't like it then sorry don't read it at all .if I can read it and so can you .
I didn't read it. Too difficult to extract meaningful thoughts without proper grammar. Took me five lines to give up! Not to mention the rambling style. Sorry, my problem, not yours. Unless you want others to take you seriously.
 
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