Solder Iron for Ivan with a built in Timeout

RE: Solder Iron for Ivan with a built in Timeout

D_Hersey — Sat, 30 Jan 2016 08:05:17 GMT

John, if only you shared the confidence in you that I enjoy! I was being lazy and hoping you would whip out your SPICE like you do for the other fellows. Now I will have to. I'm thinking we can avoid saturation by toggle XOR-ing the inputs periodically, or treating saturation as a special case, if necessary.

I've read somewhere recently that if one comes off too humbly, his fellows will reckon he is shamming. Although accusing a 'sconnie of disingenuousity is seemingly problematic, this whole chaos topic is, in a sense, looking for behavior seemingly more complex than the hardware at hand could host at first glance. jk

I've been accused of being a 'great sideways thinker' on occasion, but there is rarely a practical positive outcome of this. Even in the limited arena of E14 you hold a 7 rating while I am a mere 6, exponentially poorer in the coin of the realm. We aren't getting paid for this, so the reward must be hormonal. Status, Mr 7, brings serotonin.

We are all set up differently. Perhaps you are wired to put one foot in front of the other, judging by outcomes. Anyway, with the dynamics of my family situ I must matriculate to becoming the breadwinner. This is reality for me, a goal for which I hope to denominate in real terms rather than symbolic ones, anyway a binary outcome, a test.

Perhaps a test of my neuro-plasticity budget, perhaps a test of my aggression. Perhaps a mere search for markets. . .

RE: Solder Iron for Ivan with a built in Timeout

D_Hersey — Fri, 29 Jan 2016 04:00:41 GMT

Interesting to imagine the simpler circuits that could be chaotic. I am thinking of three presettable counters. Initially they are jam-loaded with random values, but when they time out they are loaded, say, with the sum or product of the other two counters and restarted Would that be chaotic? I've got to find it in here without triggering a crapulanch, but I have recently acquired the book Elegant Chaos by Sprott. Next, I will read it.

RE: Solder Iron for Ivan with a built in Timeout

D_Hersey — Wed, 16 Dec 2015 06:45:24 GMT

Jeez, John, wasn't trying to impugn your e--fu, just tryin' to keep you from leadin' the uts astray.

RE: Solder Iron for Ivan with a built in Timeout

D_Hersey — Tue, 15 Dec 2015 16:19:34 GMT

Since John is such an invariably kindly host, I will hijack his thread a little bit:

I have been reading a little bit about human motivators as an electro-chemical phenomenon. One of the rewards that this activity (electronics) may provide is a salience reward. Just sayin'.

I am going to argumentatively presume that this applies to myself to some non-trivial degree. Thus, I am going to get into chaos circuits merely for the salience and achievement rewards rather than to fulfil an economic narrative.

Sprott's Books and Publications

https://www.google.com/search?newwindow=1&site=webhp&q=chaos+circuits+book++&oq=chaos+circuits+book++&gs_l=serp.3...4943…

It would be cool to form a little interest group in this. The circuits are usually cheap, typically op-amp or op-amp-jellybean. They provide copious visual reward. The topic is endlessly interesting and has modern practical application in fields such as cybernetics.

RE: Solder Iron for Ivan with a built in Timeout

D_Hersey — Tue, 15 Dec 2015 15:51:20 GMT

Most of those wonderful ANs can be found online, google the titles as you remember them, like "CMOS Oscillators." A guy with NASA during the sixties gave me a databook that I have misplaced to my regret and chagrin. It was from Fairchild Instrument and Camera. It introduces the IC Op-Amp to the commercial world and describes the concepts required to deploy them. Never came upon a better basic discussion of op-amp theory subsequently. Be on the lookout for this one when cleaning out attics.

RE: Solder Iron for Ivan with a built in Timeout

D_Hersey — Tue, 15 Dec 2015 14:26:34 GMT

When we scale passives to extremes then we have to look at things like amplifier Zins, non-linearities like leakage. Jon Clift, I appreciate your taking the time to explain it and detail and so nicely. By this time, stuff like this triggers an olefactory rather than a verbal response in me.

I may have shelled out a buck for a 4060(dip) at the local electronics store a few decades ago. Times change.

RE: Solder Iron for Ivan with a built in Timeout

jc2048 — Tue, 15 Dec 2015 12:47:30 GMT

That's a neat idea; I think I want one for myself now that I'm getting old and forgetful.

I was curious about the 35 minutes for the timer. Too lazy to do the calculations, I gave it to SPICE (Tina-TI) to do. Here's the graph for a 220u charging from a 12V supply through a 2.4M resistor. The time to the switching point defined by R2 and R3 (10.46V) looks to be just over 18 minutes (1080 seconds). That's with a perfect resistor and a perfect capacitor.

[View:/resized-image/__size/600x358/__key/commentfiles/f7d226abd59f475c9d224a79e3f0ec07-750c0280-e305-4a6e-9447-66b417330a10/contentimage_5F00_180453.png:600:358]

Here's a link to TI's free spice tool:

http://www.ti.com/tool/TINA-TI?keyMatch=tina&tisearch=Search-EN-Everything

So why the difference between the calculated value and what you're seeing in practice? The first possibility is obviously the tolerance on the capacitor value. Electrolytics aren't very good in this respect: I've just looked up a few on the Farnell site and +- 20% seems to be common now, though that's much better than was once the case.

But even if you were at the extreme of the tolerance range (very, very unlikely), that only gets us to 22 minutes. The resistor also has a tolerance on its value but that will be much better than the capacitor and I'm going to ignore that for the purposes of this comment. The rest will be other currents stealing from the charge current.

The first to consider is the leakage of the capacitor. Once we get to 10.46V the resistor current has reduced to 0.64uA. [I calculated that using Ohms's law (12V - 10.46V) / 2400000 ohms = 0.64uA] A Panasonic electrolytic datasheet I looked at gave a leakage current of less than 3uA over the temperature range. In your case, for your particular capacitor and at room temperature, it must be much better than that or you would never have even reached the switching point.

The other, perhaps less obvious, current [not really "leakage"] is the input bias current of the comparator. The (TI) datasheet gives a typical figure of 0.1uA without properly stating the conditions, but the datasheet is a bit of a mess and another of the graphs shows it varying depending on the differential input voltage [which is what you would expect] - so something in the area of 0-150nA. From the circuit given in the datasheet it looks like it flows out of the chip [base current of PNP transistor], so, curiously, it will be countering the capacitor leakage to an extent.

Well, that's about as far as I can go with my musings. The point I've come to is that, whilst your circuit is absolutely fine as a one-off personal project (which is all you intended, so no criticism meant) if someone were to come to you and ask you to produce 10,000 to sell you might want to be a bit cautious. The circuit is operating in a marginal area where you would either need to do work characterising the parts yourself or take a chance (ie gamble, since money would be involved) that they were always as good as in the prototypes you had built. In practice you would probably decide to take a look at the CD4060 that D_Hersey suggests, which is a much more controlled way of timing over a period of more than a few minutes, or use the kind of small and very simple microcontroller that sells for a few 10s of cents.

RE: Solder Iron for Ivan with a built in Timeout

D_Hersey — Tue, 15 Dec 2015 09:39:20 GMT

IIRC the cap in the 4060 circuit is supply(-) refereed. So the circuits could be combined--just sayin'.

RE: Solder Iron for Ivan with a built in Timeout

D_Hersey — Tue, 15 Dec 2015 09:36:03 GMT

The 4060-type circuit is useful didactically, one can throw in dip-switches, a variable resistor, maybe a '688 equality detector -- but yeah.

The capacitance-multiplier opens the door to many interesting and difficult-to-get-working circuits such as gyrators.

RE: Solder Iron for Ivan with a built in Timeout

D_Hersey — Tue, 15 Dec 2015 02:52:18 GMT

Timer Circuits With 4060B - Electronics

https://en.wikipedia.org/wiki/Capacitance_multiplier

RE: Solder Iron for Ivan with a built in Timeout

balearicdynamics — Mon, 14 Dec 2015 20:08:59 GMT

Very good article, I should say that probably it is better than the one about the volcano. I have read this yesterday evening from the mobile (email notification) and I was fascinated like reading a short novel.

Enrico

RE: Solder Iron for Ivan with a built in Timeout

D_Hersey — Mon, 14 Dec 2015 18:07:44 GMT

'Science' just means 'seeing.'

Only scientific entities are real.

RE: Solder Iron for Ivan with a built in Timeout

CrazyFace — Mon, 14 Dec 2015 09:59:14 GMT

Absolutely love reading yours and Ivan's project blog's, Its so hard to get the kids today to show an interest, I lost my granddad at age 9 and luckily for me he had passed most of his knowledge onto my dad which he then passed on to me, but I fear that's where it will end, My 15yr old son Brendan shows no real interest in learning these skills although his 6 yr old sister Emily sometimes shows an interest now and then, I know that will wear off in time though. Keep up the good work and I look forward to the next Installment.

RE: Solder Iron for Ivan with a built in Timeout

D_Hersey — Mon, 14 Dec 2015 09:17:44 GMT

John, you outdo yourself!

CD4060B | Counter/Arithmetic/Parity Function | Specialty Logic | Description & parametrics

is another way to achieve your delay. Another idea is to use a capacitance multiplier (look it up) circuit.

-seasons greetings-

mazel tov!

Ivan matches you in charm already! So, keep a good eye on him!

RE: Solder Iron for Ivan with a built in Timeout

COMPACT — Mon, 14 Dec 2015 06:58:43 GMT

Absolutely fantastic!!

There's no time like your present!

Your workshop is also the envy of many!

1. Make sure he wears pH balanced Nitrile Gloves and avoids using PbSn solder.

He doesn't need to unnecessarily ingest it like us older folk.

Also be aware that many of the Pb free products contain carcinogenic chemicals.

Also make sure that he washes his hands prior to going to the toot.

Male electronics workers have been known to get testicular cancer!

2. Get some ESD equipment and teach him about controlled Electrostatic Discharge!

It only takes 20 volts of induced static to cause damage and contrary to the wives tales all components can be damaged with ESD.

An the other wives tale is that once a component is in circuit it's ESD safe - It isn't!