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

 

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.

 

Your flipflop is drawn wrong, and you could use a transistor to detect power failure, are both supplies the same voltage?

 

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.

 

@GopherT, what program are you using for the drawing you did in this thread? Thanks

 

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

 

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?

 

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 .

 

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.

 

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 .

 

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.

 

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.

 

.im no sitting here putting a capital letter on each bloody sentence I do .

You can capitalize the word ( I ) but not be bothered to start a new sentence with a capital letter? Wow! Some one is really important.