Who knows the OPA1632 well?

AX tech editor
Joined 2002
Paid Member
But SMT is out of reach for many of us DIYers. I certainly could never handle SMDs any more. I could've done that some 30-40 years ago, but no more.



That's one idea, and I did think of this, but then who would solder that SMD on that adapter? That's the question.

Well, I'm 72 and solder anything that's 0805 or larger. It's just a trick, not rocket science!
I couldn't do it 40 years ago ;-)

Jan
 
Very fine-pitch and leadless SMDs are increasingly hampering the DIY efforts of many of us.

Absolutely! I second that.
It's getting harder and harder for us the "older" ones.

Especially, those of us whose vision is no longer as sharp and whose hands are no longer as steady.

I guess we're having the same issues :)
There is no way I could touch anything SMT, I can't see worth **** any more and it's getting worse. And same thing with my hands, my dexterity is gone.
But I don't want to give up the hobby, so I have to stick with through hole, and even that is getting harder all the time. I'm definitely not alone in this boat.

My worst fear is that those market forces will eventually render hobbyist DIY impractical, if not outright impossible.

Me too. I already see how the hobby isn't what it used to be, with so few youngins getting into it. Same thing with computers. I was young enough when there was a huge choice of computers out there, and now it's down to just a few and the new ones aren't anything newbies can tackle and get into the hardware.

I always picture the ideal solution as being that the PCB manufacturer places and solders the SMDs of my design to the board which they produced - and, here's the key - at pricing affordable by hobbyists in the single unit quantities typical of DIY.

Yeah, but then they're the ones doing the making for us, and there isn't much left of the hobby then. I want to do the soldering, the making, not leave that to some outfit that charges a bunch of money for it.

Another solution I can imagine would be a benchtop pick-and-place machine based on low cost ink jet printer technology. Perhaps, the print-head mechanism could spray some sort of room temperature UV activated conductive adhesive on to the PCB pads, like it were printing with ink. Then the print 'print-head' mechanism is reconfigured to place the SMDs on the board. Finally, maybe the user shines an UV lamp on the PCB to activate the conductive adhesive, gluing the SMDs in place. While probably not suitable for commercial production, it might be fine for single piece DIY projects.

Wow! Oh boy! You got some ideas there. I wonder how affordable we could make this.

If someone knows of such affordedable solutions that are already in available, please advise us.

I second that too! I'd love to know how this could be done too.

In the meanwhile, some of our community are managing to do a very fine job of manually stuffing even leadless SMDs.

Yeah, I wish I could do that too. Some 30-40 years ago, that could've been within my reach.
But I suppose if only a few parts are SMT, and they can be put on some adapters, while all the rest remains through hole, then, at least for now, we can save our hobby.

I poked around for those breakout boards. There are lots of choices for huge numbers of possible situations, so I'm sure an appropriate solution can be found on a case by case basis.

In the case of the OPA1632, I would put that on an adapter that goes perpendicular to the pcb, to save on pcb real estate, and the adapter would be a SIP/SIL type.

I checked digikey and mouser earlier today for such things. Haven't found exactly that, but something close, so it must exist.

But those outfits don't put the parts on those breakout boards for us, that I know of. So who does this? And at what cost? Affordable?

There is an older chip that does basically the same thing as the OPA1632, that is available in DIP case, but it's "older" and not quite as good, and the supply voltage is a bit too low. That would be the LT1994. Not as impressive as the OPA1632, but I suppose it could do...
 
If your serious about SMT you need an oven of some sort (adapted £25 sandwich toaster works for me), and get solder paste stencils made up with your PCBs. Very professional results are obtainable.
tonearm_preamp_sm.jpg

Spot the one component that was hand-soldered(!)
 
Yeah, but then they're the ones doing the making for us, and there isn't much left of the hobby then. I want to do the soldering, the making, not leave that to some outfit that charges a bunch of money for it.
Personally, I've no hobby interest in soldering SMT. Wiring, through-hole parts, etc., okay.


Wow! Oh boy! You got some ideas there. I wonder how affordable we could make this.
The concept may seem elegant, but the implementation might be the devil himself.
 
Age isn't always the only factor, and sight not the only thing impaired. I can't touch anything SMT not just because of age and sight. Even with the best glasses or a huge magnifier, my hands aren't steady enough as they were long ago. I'm also well over 50, actually late 50s, but have other things besides age giving me impediments.

I want to continue the hobby for as long as I can, till death if possible, so I'll have to find ways to get things done, and most of it has to be sticking with through hole stuff.
 
If there are outfits that can, economically, without price gouging, do the soldering of SMDs for us, on those breakout boards, I'd like to know which ones, so I could check them out. And they really should also be parts suppliers, for only one stop shop.

Or perhaps there are solutions with some of the pcb fab houses. Because some of them do the assembly parts, and if they make the pcbs for breakout boards, they can also stuff and solder them, but then where do the parts come from? That's not an easy thing logistics wise. And probably not so cheap if they are to only do this on a few tiny pcbs and not the rest of them.

There may also be possibilities with group buys on the forums, where the one receiving the shipments is a capable assembler and who can re-ship assembled pcbs to members in the group. I'm just kicking ideas around...
 
What is the parameter VID which is Max Differential input voltage stated as +/-3V so what does this actually mean? does it mean that the input to the +ve signal input to the OPA1632 i,e +Vin ( pin 8 ) shouldn`t exceed +3V? so for -ve signal input to the opamp -Vin ( pin 1 ) ?

If thats the case what if my preamp gain stage is giving a voltage swing of +/-6V swings to the OPA1632?
 
For the explanation of VID, see p5 of https://www.ti.com/lit/an/sloa054e/sloa054e.pdf

It's a good document to read btw but here is the short version.

In practice, your situation is not a problem with the opa1632 as commonly configured with resistors in serie with its inputs, like an inverting opamp, and symmetrical feedback paths. If you're using a balanced source (differential to be more accurate) with no offset, you will have +/-6V before the resistors but close to 0V after them, at the inputs. If you're using the opa1632 as a SE to Balanced converter, with one input resistor grounded, you will have some voltage at the inputs but it will be equal at both inputs, so the differential input voltage will be close to 0.

Note however that if you send the opa1632 into heavy clipping, everything goes to hell and VID will quickly rise.
 
AX tech editor
Joined 2002
Paid Member
What is the parameter VID which is Max Differential input voltage stated as +/-3V so what does this actually mean? does it mean that the input to the +ve signal input to the OPA1632 i,e +Vin ( pin 8 ) shouldn`t exceed +3V? so for -ve signal input to the opamp -Vin ( pin 1 ) ?

If thats the case what if my preamp gain stage is giving a voltage swing of +/-6V swings to the OPA1632?

Don't read too much into it. Just plain English: differential input voltage, the difference between the two inputs +vin and -vin. That's all.
In normal operation, an opamps' differential input voltage is a few mV due to its very high gain, so it is mostly an overdrive/error situation limit.
Clipping limits are shown in the data sheet for different load impedances. Obviously, the higher the load (the lower the impedance of the load) the earlier an opamp clips.

Jan
 

Attachments

  • clip.PNG
    clip.PNG
    63 KB · Views: 110
Last edited: