-=GST=- Nemisis (cs/cz)
New Member
i have included in this post the problems that i have on a word document. i have done this because it contains pictures that are related to the text and i didnt want to post them seperatly, i will host them online and link them here if necessary or requested. a quick run down of my problem:
the opto isolator contains a LED which is used to transmit data and a Phototransistor to recieve it. this phototransistor is set up in a darlington pair array so it has the base of another transistor coming from the emitter of the phototransistor. this is sealed withing a unit and cannot be modified. basically in simulation when i connect these transistors to high and low along with my output the transistors are always on, the output from the darling pair that i use is always high. why is this? when i tried with two regular transistors this didnt happen, is it to do with the phototransistor? is it to do with the simulation? any advice on this would be great, see the word document for better details and pictures.
i have also included my circuit diagram if you wish to look at it, any critisms would be fine. it is important to note that the switiches will be replaced with outputs from a pic chip. on that note, do i need to pull down the outputs from the pic and if so would it be any different from pulling down an normal input (as shown here). also would it be a good idea to put resistors protecting the inputs of the 4014b and 4015b chips so the curent isnt drained into them?
the opto isolator contains a LED which is used to transmit data and a Phototransistor to recieve it. this phototransistor is set up in a darlington pair array so it has the base of another transistor coming from the emitter of the phototransistor. this is sealed withing a unit and cannot be modified. basically in simulation when i connect these transistors to high and low along with my output the transistors are always on, the output from the darling pair that i use is always high. why is this? when i tried with two regular transistors this didnt happen, is it to do with the phototransistor? is it to do with the simulation? any advice on this would be great, see the word document for better details and pictures.
i have also included my circuit diagram if you wish to look at it, any critisms would be fine. it is important to note that the switiches will be replaced with outputs from a pic chip. on that note, do i need to pull down the outputs from the pic and if so would it be any different from pulling down an normal input (as shown here). also would it be a good idea to put resistors protecting the inputs of the 4014b and 4015b chips so the curent isnt drained into them?