The Learning Circuit 39: Inductor Project: Battery Juicer

Hi Jan,

Thanks for the link to the ORP video. That fellow had some really interesting ideas. I think I will have to give some of them a try.

John

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 ...

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

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...  

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.

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.

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

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

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,

I have been experimenting with the circuit and I found that the 2N2222 will allow the battery to be drained down to about 0.6 Volts. If on the other hand you use a Germanium NPN transistor the circuit will continue to drain the battery all the way down to 0.2 volts before it stops working. If we are going to Juice the battery we might as well drain it as low as possible.

John