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jimdkc

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  • jimdkc commented on YADUKRISHNAN K M's instructable Working "MEGA 555"

    Very cool project and great execution! Not only is the 555 timer a very useful IC, but one I highly recommend that beginning electronics enthusiasts study. Once you understand what's going on inside of one of these (at least at the block diagram level) the more useful they become. I especially like that you used salvaged components and materials.

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  • Would be cool to hide some kind of battery-powered remote control in the base...

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  • Not if you have a 1K resistor in series as suggested...

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  • Easy way to help remember which lead is which: Flat Fat Cat...The FLAT on the case and the FAT terminal inside the LED are the CAThode.Also, the Anode has the Arrow on the LED schematic symbol.

    Surface mount LEDs will usually have some sort of indicator... a dot, or line, or notch. That indicator USUALLY indicates the cathode, or negative terminal.Tweezer-style test leads are handy to have if you can find them for testing surface mount devices.

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  • Just saying... Anybody who works for a company with more than 50 employees is likely to be subject to a corporate security policy. In a world where chief executives get personally sued over security breaches, this sort of thing is taken very seriously. You had a legitimate use for this device... circumventing security so you can leave your computer unattended without securing it is not a legitimate use and could get the person who does that in deep trouble!

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  • Careful! Where I work, anybody caught using such a device would be subject to disciplinary action, up to and including termination, for circumventing security policy!

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  • This continues to be one of my favorite effects to do. I also found the perfect suit to wear with this!

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  • jimdkc commented on lonesoulsurfer's instructable Cigar Box Synth

    Interesting circuit. Big fan of Forrest Mims III circuits (I had most of his old Radio Shack books) and a big fan of cigar boxes. Here's a tip: If you put a piece of scrap wood behind your cigar box lid, you can minimize splintering when drilling it.

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  • I will definitely try this! I've successfully used the stovetop method many times, but it does require a good deal of attention to keep the cans completely submerged. I was considering trying the pressure cooker method, but this looks even easier and safer! Store-brand or generic sweetened condensed milk works just fine and is much less expensive than the "name-brand" or commercially canned Dulce de Leche. This stuff is great on ice cream (if you can avoid just eating it straight from the can!)

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  • Or, S8550's are just as cheap!

    Cool! You can replace the borrowed or missing 8550's with almost any small signal PNP switching transistor, such as a 2N2907 or a 2N3906.I buy 2N3906's (and the NPN complement 2N3904's) by the hundreds on ebay or geek.wish.com for a couple bucks!

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  • Check your transistors carefully. TWO are PNP, and THREE are NPN. Make sure the PNPs are in the right place.I believe, going by the legends on the PCB, that Q1 and Q3 should be PNP (8550) and Q2, Q4, and Q5 should be NPN (8050).All the driver positions on the board are labeled 8050. Q3 is mislabled.If you mixed up these transistors, that would explain your odd results!

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  • Would be cool to wire up a couple of tilt switches to it and program it so you can flip it over and have the LEDs "flow" back the other way.

    I believe, on your LED Dice circuit, if you replace each of the 10K resistors that go between the 4017 output pins to the transistor bases with a series diode + 10K resistor combination, your circuit will work much better:4017 Output Pin----|>|----^v^v^v----Transistor baseThis will properly isolate the 4017 outputs from each other...You can do this by desoldering the 4017 end of each resistor, solder the anode of a diode (1N914 or 1N4184 small signal diodes should work nicely) in each newly vacant hole, the solder the cathode lead of the diode to the newly freed lead of the resistor. You will need 8 diodes.I have two of these kits waiting to be assembled. Maybe I'll build one with and one without diodes to compare the difference!

    OK... I was confused by the fact that there is no connection to pin 2, the Q1 output of the 4017. However, I did not notice that one of the LED driver transistors is a PNP. So when the Q1 output goes HIGH, all the other outputs are LOW and that PNP transistor turns on.I also found this schematic, which also appears to be nearly identical:http://www.555-timer-circuits.com/led-dice.htmlI'll build one of my kits this weekend and see how mine works.

    Oh, wow! I just realized that pin 2 of the 4017 is not connected to anything at all... That's how you can throw a "0"! Yikes!I have a new project... trying to fix this circuit!

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  • Cocobolo may be the most fun wood name to say. Well, either that or Bubinga...Nice table!

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  • jimdkc commented on mikeasaurus's instructable Drill Press Drum Sander

    As others have mentioned, a drill press mechanism is not designed for lateral pressure. I'd recommend using this only for very occasional use, and only with very light pressure (let the sand paper do the work, not pressure!) If you see yourself doing a lot of this type of sanding, spindle sanders start at about $100.

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  • Those are actually all standard 2-5% resistor values, but they are all readily available in 1% resistors, too. I had all of these values in a resistor kit purchased on eBay.Search for "1/4w 1% resistor assortment"I bought one of the 3120 piece assortments (20 each of 156 values) for under $15 shipped.

    Also, if you choose 300 ohms as your R2 value, R1 can be hit exactly using standard 1% resistor values for all desired voltages:Voltage - R1 = R1a + R1b1.5v - 60 = 30 + 303v - 420 = 220 + 2003.3v - 492 = 430 + 625v - 900 = 470 + 4306v - 1140 = 750 + 3909v - 1860 = 1.5K + 360

    Nice job!I'm mulling over a dual-regulator version so I can have different voltages on the 2 busses...

    Also, if you choose 300 ohms as your R1 value, R2 can be hit exactly using standard 1% resistor values for all desired voltages:Voltage - R2 = R2a + R2b1.5v - 60 = 30 + 303v - 420 = 220 + 2003.3v - 492 = 430 + 625v - 900 = 470 + 4306v - 1140 = 750 + 3909v - 1860 = 1.5K + 360

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  • I had a bird problem, too. I solved it by tying long strips of reflective mylar (previously I used strips cut from an old insulated shopping bag, this year I purchased mylar "space blankets" on eBay) to the tops of each cage. They move with the slightest breeze and reflect the sunlight. The birds steer clear!

    Yep. A set of 14" bolt cutters will run about $15 at your local big-box hardware store.

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  • I live just east of Kansas City, Missouri. I have lived in Southern California, too, and the best tomatoes we ever grew there was with the aid of chicken manure, applied a few weeks before planting. This year, put a handful of worm castings and a little epsom salts in each hole where I planted my tomatoes. All my plants (except 1!) look really good this year, so far.

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  • Those are some nice cages! I got tired of flimsy commercial tomato cages a few years ago and bought a 150 foot roll of 6x6x10x10 concrete reinforcing remesh. (6x6x10x10 = 6 inch x 6 inch opening, 10 squares or 5 feet high, and 10 gauge wire). I cut off 6 foot lengths and zip-tied the edges together to make cylinders (roughly 2 feet in diameter). They are NOT rustproof... but it will take YEARS for them to rust through! I staked them to the ground this year with 3 foot lengths of rebar driven 2 feet into the soil, 3 per cage (previous years I used 2 foot wooden stakes driven 1 foot deep... but I did have 1 cage fall over!) And I still have most of the roll of remesh in my garage! I've also made 2.5 foot extensions to attach to the top of the cage when the plants get really tall. One of my…

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    Those are some nice cages! I got tired of flimsy commercial tomato cages a few years ago and bought a 150 foot roll of 6x6x10x10 concrete reinforcing remesh. (6x6x10x10 = 6 inch x 6 inch opening, 10 squares or 5 feet high, and 10 gauge wire). I cut off 6 foot lengths and zip-tied the edges together to make cylinders (roughly 2 feet in diameter). They are NOT rustproof... but it will take YEARS for them to rust through! I staked them to the ground this year with 3 foot lengths of rebar driven 2 feet into the soil, 3 per cage (previous years I used 2 foot wooden stakes driven 1 foot deep... but I did have 1 cage fall over!) And I still have most of the roll of remesh in my garage! I've also made 2.5 foot extensions to attach to the top of the cage when the plants get really tall. One of my plants last year grew to over 9 feet tall in its 7.5 foot cage!

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  • Agree. I would encapsulate all the exposed wiring in a blob of silicone sealant.

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  • jimdkc commented on randofo's instructable DIY Guitar Pedal

    I like those dial plates! It's worth noting, if you want to build other projects to match this, that they are less expensive the more you buyYou get 2 for $4.34 ($2.17 each, the link you provided)Or... you can get 5 for $6.44 ($1.29 each) https://www.amazon.com/dp/B0147XRJ0OOr... you can get 10 for $8.41 (84¢ each) https://www.amazon.com/dp/B0147XDQQA

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  • jimdkc commented on pandyaketan's instructable LED on AC Mains

    You do need the diode because an LED can only tolerate about 5-6 volts of reverse voltage.

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  • jimdkc commented on Nikus's instructable 555 Useless Machine

    No. You need to either use a DC gear motor or remove the servo control board and wire directly to the motor. Also, the servo should be a continuous rotation type.

    Yes, an Arduino is overkill for this project. But, so is a 555 timer.

    Yes! Absolutely! The 555 is a great chip to have in your arsenal! No better way to learn it than to actually use it!

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  • If you have a Firehouse Subs near you, they sell their bright red 5-gallon pickle buckets for $2 each. Proceeds go to provide life-saving equipment and resources for firefighters, police, and EMTs. The buckets do smell like pickles, but that shouldn't matter for this use! Good sandwiches, too!

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  • A Zipperface is always a fun costume to do!

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  • Well... it could be a bridged amplifier... except the input of one of the amps is grounded, so only 1 amp in the chip is active! To make it a bridged amp, you'd have to unground pin 6 and feed an inverted copy of the input signal to pin 6.The way this amp is designed, half of the amp chip is wasted.

    OK... I see from the datasheet of a TDA2822 that this is a correct bridge configuration. Normally for a bridged amp, you have to drive both inputs. Apparently this amp chip takes care of that internally.

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