Inductor Project: Battery Juicer -- The Learning Circuit 39

Good episode.

I did cringe a bit when you used solder to make your connects. Try using the component leads as soldering posts so you make good wire on wire connection. You will get better results.

Next you need to learn how to use heat shrink tubing to cover the wires. It will work better than tape.

Other than that, great job.

DAB

Hi DAB,

I'm not sure which part you're talking about me using solder to make connects. Could you clarify? I keep a tiny bin of lead cutoffs for making jumpers when soldering, though I know I do sometimes take shortcuts if the connections are pretty close. Though I don't remember having to jump anything in this project.

And yes, I love heat shrink, though I'm often a cheap skate and save it for no good reason. I actually used some on the project video we just shot for components that will be plugged and unplugged from the board. It's nice stuff, but when I don't have any on hand, tape does work in a pinch.

Karen

Hi Karen,

It looked like you just used a solder bridge on several of your board connections.

I noticed some of the lead wires just kind of floating until you tacked them down with solder.

I know this technique is similar to SMD attachment, but I prefer to see good solid wire twisting to make sure the wires themselves are touching.

DAB

Hi DAB,

When you and I were learning the mantra was make a good mechanical connection before you solder. I have personally disowned that over the years as every time I have doe it I have regretted it when I had to modify or fix the junction in question. If making a good mechanical connection were to be a measure I would win the prize for the worst solder technique. Based on what I could see of the finished product in the fast frame sections of Karen's presentation I think everything looked good.

John

Hi John,

I have chased cold solder joints enough to know that a good solid connect is the best.

Yes, the low lead solder gives you a better connection, but it is still better if you take the time to make good connections.

If you rely only on the solder, you can find interesting effects invading your circuit.

Granted it may make no difference in simple circuit, but you just never know, so play it safe.

DAB

Hi DAB,

Here is a situation similar to Karen's where I am soldering and connecting a resistor to a transistor on a piece of protoboard. I am open to learning from you how you would improve this technique.

I apologize for the photos but closeups like these are at the limit of my camera and the protoboard is difficult to contrast against.

The long leads are those of a resistor and I have marked one of the lead positions with a black mark. It is my intention to connect this resistor with the lead of a transistor also marked in black. The pads are 1/10 inch spacing. In connecting the resistor to the transistor I also want to create a rail onto which other components can be connected. I begin by creating a solder joint on the transistor lead's pad.

I have also trimmed the resistor lead so that it ends right at the transistor pad. Next I tin the end of the resistor lead and hold it down as I solder it to the transistor lead pad. I have bent the lead in such a way that it does not run down the middle of the holes in the pads between the resistor and the transistor. I then solder the pad where the resistor comes through the board.

As you can see the holes are not blocked between the resistor and the transistor. Other components can then be inserted and soldered to the bent resistor lead.

From my experience any mechanical wrapping or attaching of the leads takes up too much space and makes the possibility of shorting between pads much more likely.

Let me know what you think.

John

Hi DAB,

Here is a situation similar to Karen's where I am soldering and connecting a resistor to a transistor on a piece of protoboard. I am open to learning from you how you would improve this technique.

I apologize for the photos but closeups like these are at the limit of my camera and the protoboard is difficult to contrast against.

The long leads are those of a resistor and I have marked one of the lead positions with a black mark. It is my intention to connect this resistor with the lead of a transistor also marked in black. The pads are 1/10 inch spacing. In connecting the resistor to the transistor I also want to create a rail onto which other components can be connected. I begin by creating a solder joint on the transistor lead's pad.

I have also trimmed the resistor lead so that it ends right at the transistor pad. Next I tin the end of the resistor lead and hold it down as I solder it to the transistor lead pad. I have bent the lead in such a way that it does not run down the middle of the holes in the pads between the resistor and the transistor. I then solder the pad where the resistor comes through the board.

As you can see the holes are not blocked between the resistor and the transistor. Other components can then be inserted and soldered to the bent resistor lead.

From my experience any mechanical wrapping or attaching of the leads takes up too much space and makes the possibility of shorting between pads much more likely.

Let me know what you think.

John

Hi John,

From my training, a proper connection would have you wrap the lead of one component around the lead of the other and pinch it together before you solder.

That way you have wire on wire contact and are not relying on the solder, to support the electrical connection.

DAB

That's really interesting. When soldering on protoboard, I hadn't heard of wrapping the leads together.  It makes plenty of sense to me if the leads are loose, but on a board I believed that soldering to the pads was reliable enough. Granted, I am making fairly simple circuits, but I have taken a lot of my soldering cues from Ben.

DAB I'd not heard of using this approach on protoboard or pcbs, just wire to wire connections. I can see how it would make repairs or rework more challenging and like John I used to do that but avoid it now,

Is the idea of twisting an electrical or mechanical thing?

For something like this where there's strain on the cables, what I'd do would be to drill a couple of holes and pop a cable tie through.

If I was worried about a heavy component causing strain on the board I'd either mount it off the board with connectors or glue it down for extra support.

makerkaren great episode, a useful example of these fundamentals. What controls the frequency of oscillation? Shouldn't there be a series resistor for the LED for when the battery is full?

And a general thought, perhaps you could make the circuit long and thin and fit it into the battery case alongside the other battery.

Hi Karen,

Back in my tech school days, yes it was before you were born, they were very insistent that we first make firm mechanical connections before we added solder.

If you have the wires loose and then hold them down with the solder, you add mechanical stress to the connection.

The big issue in all of these comments is to ensure you have a good electrical connection.

If you do not get a good solder joint, then you introduce resistance and or intermittent connection. Both are bad for certain types of circuits.

Think of it like placing two lengths of hose near each other and expect the water to magically continue flowing from one to the other without spilling out.

DAB

Hi Andy,

As long as you do not have cold solder joints, you can get away with just tacking things down.

If you get a cold solder joint, you can spend a lot of time trying to find and fix an intermittent problem.

I was taught to eliminate that possibility by making a firm physical connection in addition to the solder connection.

In the end, it is more reliable.

DAB

Hey Dab, I suspect this makes a lot of sense when you are making production items using something like tag board. My personal experience is that it's always those twisted joints that cause the trouble. I was pondering why that was and wondered if it was a larger thermal mass and a small soldering iron.

makerkaren  wrote:

 

That's really interesting. When soldering on protoboard, I hadn't heard of wrapping the leads together.  It makes plenty of sense to me if the leads are loose, but on a board I believed that soldering to the pads was reliable enough. Granted, I am making fairly simple circuits, but I have taken a lot of my soldering cues from Ben.

I think that is how these boards are supposed to be used.

I suspect this makes a lot of sense when you are making production items using something like tag board

I recall when working with tag board at college there was mention of soldering alone not being considered as a 'mechanical connection', so leads had to be wrapped and squeezed prior to soldering. I assumed that this partly stemmed from the days of much larger and heavier components, which with vibration and thermal cycling could perhaps easily break apart the solder joint.

This was followed by the wire-wrap class, which was considered both mechanical and electrical, so no worries there then.

Then came the strip board class and any prior concerns about wrapping or squeezing or mechanical connection from the previous two classes, appeared to vaporise as quick as the flux on the hot tip of the soldering iron...  

Hi Andy,

It all depends upon the circuit you are making and how much time you have to track down issues.

For simple circuits, it probably does not matter.

If you get into any circuit where there is frequency, inductance and capacitance sensitivity, then it will make a lot of difference.

DAB

DAB  wrote:

 

...

If you get into any circuit where there is frequency, inductance and capacitance sensitivity, then it will make a lot of difference.

 

DAB

For those exercises, I prefer full copper clad boards, cut out islands with an exacto knife or a small hole saw drill,  and dead bug layout.

Or - very inspiring - using wae2w's methods:

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These boards can be found in 'for cents' throwaway bins at any school or shop ...