Do you use sockets for opamps? Re OD250

[dachshund]

I'm having a vexing problem building the OD250. I get no output from the circuit.

I've wired it up with the vero, went back and breadboarded it to check the circuit and measure dc voltages. Then I tried with my own layout (it's a simple circuit), and still get no output.

I have a socket for the chip. I'm using a LM308N. I have 4 of them, so I tried each one. Two of them measure < 1.0 VDC at pins 2 & 3 of the opamp. The other two chips get me the 4.5 VDC there, which is what I'm expecting.

Those IC sockets are pretty simple beasts. Do you all use them with opamps, or just solder the chip in.
I'm really scratching my head on what I'm doing wrong. And I have read the "what to do when it doesn't work."

The circuit: http://www.generalguitargadgets.com/diagrams/dist_250_sc.gif

[Mark Hammer]

1) Sockets are a convenience if you are concerned about heat or static damage to the chip, wish to experiment with different pin-for-pin replacements, or are simply one of those folks who has more projects than chips and has to "borrow" semiconductors from board A to make board B work.  They are not a requirement, though.

2) The LM308 generally wants to have a compensating cap between pins 1 and 8.  That may be your problem.

[markm]

The LM308 is a Dual Op-Amp is it not?
The schem calls for a Single.

[Mark Hammer]

Nope.  The 308 is a single op-amp, as used in the Rat.

[markm]

Nope.  The 308 is a single op-amp, as used in the Rat.

Ahhh Yessss 
so it is!   

[dachshund]

I found the problem, one connection wasn't soldered !!!!
It works now. What a relief.

[petemoore]

  Yes.
  I burned up a 386 before I discovered there are IC sockets...no big deal...but of course the board was shot too then.
  I think it's tricky and troublesome to solder IC's direct to board, not worth the risk unless you know what that is and can keep the IC happy during construction.

[pi22seven]

I use a socket on all ICs and most transistors.

ICs are too big of a PIA to desolder if needed.

[R.G.]

I think it's tricky and troublesome to solder IC's direct to board, not worth the risk unless you know what that is and can keep the IC happy during construction.

I used to feel that way until I noticed that most ICs are cheaper than good sockets. Add to that socket unreliability for cheap sockets, and I just quit buying sockets for most chips.

ICs are too big of a PIA to desolder if needed.

I used to feel that way, until I realized that if I considered the IC to be expendable, then I could just clip off the leads on the component side, lift the pins out one at a time and stick a wooden toothpick in the holes and solder in a new one very quickly. Now I don't sweat the desoldering. Snip, snip, lift, lift, poke, poke, new IC.

But I agree that for beginners this is a hard state of affairs to come to.

[Ronsonic]

I'll socket something I'm going to experiment with things like whether different chips sound different in this circuit. Otherwise I just go straight into the board with them. If one needs to come out, I just run a bead of solder along each row of legs heat one side and pull until it's partially out, heat and pull the other row and then finish the first row. Doesn't take long at all.

Ron

[petemoore]

  If all you have to heat is that trace and that pin...
  But for perfboarding, often there is the pad, pin, and more than one lead and another pad..wires etc. which all need heated at the same time, and enough so that the pad 'takes the solder, for these situations a socket will prevent the possibility of overheating the IC.

[Ronsonic]

Only for the first 50,000 or so joints, then you start getting good at it. 


Ron