#1
Hello, I am working on a pedal and i would really like to use an 4559 IC but I think it would be really cool to build one out of transistors and resistors per the appnote. I figure that it would be both a learning experience and it might even sound better. (sometimes I like doing things the hard way).

The only problem is that none of the components are labeled on the appnote. I know very little about IC's but I have heard that they don't have formal capacitors, rather they use the "built in" capacitance that is kind of just there.

So if you guys can offer me any help or advice or even correction because I'm a total idiot I would greatly appreciate it.

Thanks!
#3
it probably isnt feasible to build the thing out of discrete components. mostly because, as you said, there arent values for anything. so you dont know what kind of transistors to use, values for resistors or caps, or anything else. while it would be an interesting project, you are going to have to find a much better datasheet if you want to try that. there simply isnt enough information to really do anything with that.
#4
Making it from just transistors and resistors is going to be extremely difficult for you because all of the transistors in that op amp need to be matched. Not just for things like hfe and other measurable parameters, but a lot of other parameters that you will not be able to match for.

Now... you can make an op amp like this, but since you can't match all of those parameters you can't guarantee proper operation, or that it will even function as intended.

For the most part all of those resistors are going to be setting current mirrors up to get high gains out of the circuit. Jim recently built a CA3080 out of discrete parts and could not get it to sound very good so I doubt many of the people here could do it. I take classes to design them so I have the whole book of equations to do this kind of stuff... if you can tell me how to measure critical mobility and other things with a given transistor... then we might get somewhere.
#5
You could probably build one of the first ic's ever.

People used to do it all the time using wire wrap.

but...once you get over like 10 components you will be totally boned.
Prs se Holcomb is the answer
#6
Did he build the CA3080 for like a ross clone or something?

And thanks for all your help!
#7
Quote by Mr_Zap
Did he build the CA3080 for like a ross clone or something?

And thanks for all your help!


Yep, it did not work out well and acts quite strange honesty. I've been trying to come up with ideas as to why it could possibly be doing that but its extremely difficult without detailed information about all of the transistors in the CA3080l
#8
i built a discreet CA3080A (Intersil). i tried it in my 83 dynacomp (in an attempt to get back the sound of the original RCA part that i fried). it sounds pretty off and acts strange. here's a layout. Diodes are 1N914. Transistors are just general-purpose types. I tried to match the hfe as best I could. might get better results using the B-E junction of transistors as the diodes. Q1-6 are PNP and Q7-11 are NPN.



there are lots of things they can do with IC's that you just cant do with discreet components. insane matching tolerances, for one thing. and something about transistor sizing. honestly idk much about building discreet IC's beyond the fact that they are difficult to get to act right. XGamerGt04 knows alot more about this than me though.
#9
A major problem that I have failed to mention is that the transistors that you can buy off the shelf are not at all like the ones used in ICs. Discrete components are designed so that you can use them for a lot of other reasons.

Its like with most MosFETS available. A CMOS Inverter has two transistors that each have on resistances in the 10s of Kohms range. You can't buy mosfets with on resistances that high anymore usually.