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According to Pete: Point-to-Point Soldering

Practice makes perfect...ly acceptable, folks.

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Are you afraid to color outside the lines? Do you cringe at the thought of free-handing your way through a project build? Do you experience an unreasonable amount of solace by having all those unruly components locked down to a PCB while you mutter, "Everything in its place, yes, precious"? Well, grab your fave hand tools, 'cuz it's time to step outside your comfort zone. In this episode of ATP, we're going to take a closer look at point-to-point soldering.

Questions? Concerns? Ideas for the next According to Pete? Accidentally soldered your hands together? Leave it all as best you can in the comments, call a doctor, and we'll see you next time!

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Comments 26 comments

  • Mine's another tube circuit: a musical Jacob's ladder. The output of a big beam power tube drives the primary of an oil burner ignition transformer lashed to V-shaped wires. Plug in a guitar, hit a string, and hear it an a zappy arc. All point-to-point wiring with terminal strips, connectors, and tube sockets. view of circuitry

  • Building guitar amps, it's not strict p2p wiring that I use for that (though some do).

    What I apply is a technique called 'turret-lug' construction. Take a piece of 1/8" Garolite, drill a pattern for the buses and major blocks of the circuit, insert the turret lugs through the holes, swage them on the back of the board, and go to town soldering the topside.

    Another tip is to use silver-coated/PTFE-insulated avionics wire. Not because the silver imparts any magical sonic qualities but because it is stiffer. In a high-gain guitar amp, how you route the wires is everything and the stiffness of the silver plated hookup wire really helps.

    The PTFE insulation stays nice and intact without shrink-back after resolderings, even many times. Best to get wire strippers that know how to work on PTFE.

  • Last year I made a series of small sculptures, using the components of functional blinking LED circuits (based on a 555 timer). This one was the largest. I got extra parts to work with by replacing the resistors in the circuit with a bunch of small resistors in series. I mounted the battery and switch on the back side of the board.

  • Only thing I would add is, pick up the cold soldering iron the same way you pick up the hot one, I swear they look the same.

  • I built christmas cards a few years ago that had flashing LED's built-in to them as a kind of free-standing tree.

    The circuitry for them was a simple flashing circuit built around a 555 timer that I point-to-point soldered and embedded in epoxy in the center of the trees. I unfortunately don't have any pictures of the finished product at hand, but I do have a leftover prototype circuit that I didn't end up using. The final product had the blue wire reversed and replaced with green wire because christmas.

  • Nice video. A couple of things you might find amusing...

    Nearly a year ago, before surgery to repair a broken wrist, the doctor asked what sort of activities I used my hands for. One of the first things that came to mind was soldering, and I mentioned that I can solder 0.5 mm pitch devices by hand (albeit I need a descent microscope to see what I'm doing!). He said he'd heard enough, and left it at that. (I later realized that this is down on the scale that eye surgeons work on -- I later mentioned the incident to my eye doctor, and he said "Well, you've got the dexterity to be an eye surgeon".)

    I recall about half a century ago, when I was just learning to solder (remember soldering guns?) I got very frustrated trying to solder a model out of bits of piano wire. Never did get that to work. (Actually had to buy a new gun a few years ago to remove and replace the heavy wires for 12V DC that needed to be able to handle 30 or 40 amps for some old mobile radios.)

    I remember "letting the smoke out" of an almost new DMM about 25 years ago by trying to measure the plate voltage on a tube. I know you'll be wary of it, but I'll mention it for the "newbies" in the audience: Be VERY aware of the voltage ratings of your instruments when working around tubes. A lot of the digital oscilloscopes, especially the "pods" that plug into a computer, have a maximum input voltage of only a few tens of volts -- and voltages in the hundreds of volts are not uncommon in tube circuits, and even well over a thousand volts aren't rare. (The anode voltage on an old CRT TV or oscilloscope can be several thousand volts.) This is enough to fry everything from that nifty scope pod, though the computer, through the ethernet router, and even the cable modem... let alone the "operator"...

    A few years ago, the dentist wondered why I cringed when he was trying to use a sparking thing on my gums... despite heavy doses of the numbing drugs...

    Some of my "point-to-point" stuff has had PCBs in the "middle" -- I built a "flashy name badge" that would flash out my name and ham radio call sign in Morse code -- the "physical support" is a 3xAAA battery holder, with an Adafruit Trinket on the back and some NeoPixels on the front. (It also includes a light sensor, and adjusts the brightness for the ambient light conditions.)

    • Very cool, thanks for the stories.

      • Heard a related story at a ham radio meeting last night: In the late 1960s, there were emergency vehicle radios that were mostly transistor (on PCBs) but had a vacuum tube (point-to-point) as "final" (the power amplifier), because at that time, there were no transistors that could handle 100 W at in the VHF range. Well, there was a (two-way) radio from an ambulance that the crew kept complaining of an intermittent on transmit, but in the shop it couldn't be duplicated, no matter what abuse the shop tried on the radio. One afternoon, the sun was shining through the window onto the radio, and someone noticed that the filament (heater) leads on the tube socket had never been soldered! Most of the time, the mechanical connection was enough, but once in a while, it would lose contact, and unheated "glow-FETs" don't work too well...

  • I don't know if you'll see this comment over 1 year later, but...

    For your exposed HV connections have you considered using something like corona dope (https://www.mgchemicals.com/products/insulating-coatings/red-insulating-varnish-4228) on them once the circuit is finalized? There are various types, but the one I linked to above is a nice pleasing red (very near to SparkFun red).

  • The Soldering tutorial is simply superb. Thanks.

  • Thank for the amazing soldering tutorial

  • Pete, can you do an episode on Contact Resistance? My FlashForge printer died and I found that the connector a 'KEFA' was seriously fried on the ground pin (burnt to a crisp). I managed to get a Molex which was rated for an additional 5A. Talked to my boss and he said that even Molex connectors suck because most are Tin plated. Unfortunately gold plated connector have an 11 week lead time and a minimum quantity in the thousands..... What can I do? What should I do? How to fix? All these and other interesting answer I await thee in a video.

    • I'm not Pete, but I'll point out that I buy Molex 0008580122 contact pins for that situation. They're gold plated, and Digikey offers them as their part number WM2304-ND and have 5800 in stock for immediate shipment. There's no minimum quantity either: you can buy a single pin for 54 cents, or 50 for $20.28.

      • (Thanks for answering, Madbodger) Contact resistance. That's a good one, thanks! That and flex circuits. I hate flex circuits.

  • Here's my version of a 1-tube regenerative receiver from Practical Electronics. The original design by Dave Green, W6FFK, was pure 1967 amateur tech with an aluminum Minibox chassis. I substituted the parts I had in my junkbox where necessary and built it on a chassis made from double-sided coppper-clad board (so even the chassis is point-to-point soldering). Anytime I needed to solder to ground it was a simple step to just solder to the chassis.

    As you can see, the parts go point-to-point from the tube socket to ground, from the terminal strip to ground and from the tube socket to the terminal strip. The red wire from the power supply is +125VDC, so definitely don't touch the terminal strip until the power supply filter caps are discharged.

    My only issue with some of the ptp creations I've seen is the shock/vibe sensitivity. Many of them are way too fragile.

    1-Tube All-Bander 12AT7 regen

    • Nice project! It's true, making PTP circuits can be challenging with regard to vibration and safety. Maybe that's why I dig them so much.

  • My absolute favorite point to point soldering example can be found at: http://www.instructables.com/id/Crystal-cMoy-Free-Form-Headphone-Amplifier/ It's a thing of beauty!

  • Oh, 'bout four decades ago, I recall piggybacking 2112 RAM chips and soldering pin-to-pin on my KIM-1 to double the memory to a whopping 2 KB. I used an early generation battery-powered solding iron, a Weller I think. My girlfriend had to hold the the piggybacked chips steady until I soldered a pin or two.

    Recall, also, that all consumer electronics was soldered point-to-point before the advent of printed circuit boards around 1960 or so. My first shortwave radio, a Hallicrafters S-38E was point-to-point. Inside, it looked like a semi-organized rat's nest, and gave the sense of mass-produced DIY. Ah, nostalgia just ain't like it used to be.

  • Pete! You should have mentioned dead-bug construction while you had an example open on your bench!

    Also, a series on “Circuit Building Techniques That Time Forgot!” would be good, including Dead-Bug, Cordwood Construction, and Wire Wrap.

    • That's an interesting idea. I honestly can't abide wire wrapping, and can't figure out why people still do it. Just solder the wires! I wouldn't say that dead-bugging is a forgotten thing, though. Hey, sometimes you gotta prove a circuit before you have a PCB. But I'll normally do that on a perf board or some other PCB just to get a workable hard point.

      • ...can’t figure out why people still do it

        First, some of us actually enjoy wire wrapping, as well as soldering. When done with manual tools (stripper, wrapper, etc.) it's got a satisfying mechanical zen that soldering irons can't match, much like caulking the planks of a clinker-built boat.

        Next, there's no danger of setting the house on fire or burning a hand or a favorite pet's nose. There's no toxic chemicals (lead, rosin, etc.) It's much easier to undo than a solder joint and it's easy to inspect for quality. The only consumable is 30-guage wire. There's no wet sponge. There's a basic simplicity about just wrapping a wire around something, as well as the magic of it being a gas-tight mechanically sound connection in spite of the simplicity.

        Mind you, I still solder a lot, but there are times when wire wrap is more soul-satisfying. Hope this helps.

        • Those are reasonable answers, and I can certainly get on the zen-bus about the sort of satisfaction I get from doing this sort of work with my hands. And there are those that would argue that soldering is going a similar way as wire wrap, that it's unnecessary (or less necessary) in the larger scope, that everything is going towards a plug-n-play sort of thing, that you can just plug in a few sensors to your pi, work up a new phone app for it and hit San Jose to get bought up by Google. But I'm not one of those. I'll always be a hardware guy, so I know exactly where you're coming from.

      • Oh the days of debuging a 3000+ wirewrap backplane.

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