ok here is where I am on a project I am building a TTL interface however I need to invert output of the RTS line as the chips idea of high is 0v Low is 3.3v I have HD74LS04P Hex inverters and the 2N3904 Transisters however I have not managed to get the circuit working so if someone could be so kind as to help me out I would be very grateful

Thanks,
Yonu

 

Please show us the circuit to which you want to make an interface and the circuit you tried.

How fast do you want this inverter to be?

 

Sorry for the delay here is the sircuit I am working on however inplace of the relay I am using a LED for testing and omiting everything to the right of the relay as to the speed I need it to be as fast as possible

Thanks,
Yonubear

 

q2 is connected incorrectly to your relay,should be connected to the anode of your diode across the relay,the other side should go to supply. q1 has no resistor on its base....Heres what i mean with the relay connections

 

ok thanks and I wan't sure about the relay sometimes using other peoples design is a pain what size resistor would you suggest

 

inplace of the relay I am using a LED for testing ............ as to the speed I need it to be as fast as possible

Will the final design have a relay or something else?

what size resistor would you suggest

How much current does the relay (or whatever else you will use) draw?

 

the relay coil is 20ma and ust for good measure lets assume 20ma on the LED I am sure it is less(don't have the spec sheet on them purchased awhile back)

 

very stupid question warning.

I assume since a LED is a Diode I can use it inplace of the diode? and if yes or know do I simply put the diode across the 2 terminals on the relay?

 

I decided to play with resister values and enedup wiht 0v at 470ohm so I want to say think you to everyone as I got the circuit working thanks to the diagram sheldons poested so agin thanks.

Thanks,
Yonubear

 

heres an easy way to add an led.....