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  • Stop Using Ferric Chloride Etchant!  (A Better Etching Solution.)

    what if i happen to have a spare medical oxygen tank? asking cause i know little about chemistry but want to avoid things that go boom and etch with out the help of fire department.

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  • JohnathanW15 commented on Nematic!'s instructable How to #2 - Use LTC3780 1 week ago
    How to #2 - Use LTC3780

    what resistor value on the CC terminals would set it wide open (no current limit) Im trying to save space and the pots are slightly higher than the caps so Im taking them off for a thinner case. I need 24-26v (currently resistors replacing CV are giving 26) and no limit on amperage. The device attached draws 2amps max but im not quite sure how to tell if its limited by the 3780/psu or not as i cant force device to max power and dont have power resistors I wouldnt turn red hot

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  • JohnathanW15 commented on lancandy's instructable $30 High-Speed PCB Drill Press1 week ago
    $30 High-Speed PCB Drill Press

    ever heard of rental? I can get an air compressor for 4 hrs for 15 bucks at mennards. if you are doing so many you need it for more than 4hrs, you should probably be sending out to have your boards made. also, If you dropped the attitude you have you might manage to make friends with someone who owns a welder. in my experience most people that own them are happy to do a project as small as that for you/with you for a 6er of beer you will probably consume with them...or just conversation

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  • not an expert but I seem to remember from college astronomy lab and diy flash light builders forms that the moment you add mirror or lens you have losses. so claiming a 100watt light will be a 100watt laser makes you sound like a bit of a nut. also, i hope 8 years after you are posting this all lights you have are consuming something more like 5-20 watts if no get some LEDS bro

    I hear dissimilar ages are more accepted in germany

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  • JohnathanW15 commented on synthdood's instructable DIY PCB Using Liquid Photoresist 2 weeks ago
    DIY PCB Using Liquid Photoresist

    er...any kind of etch resistive ink, wouldnt need to be photo

    question that strikes my mind is, can you fill an inkjet carriage with the PR ink and then modify the rollers to pull a pcb (in a 8x11 sled w/cut out) through

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  • How to Make a Printed Circuit Board (PCB) Using the UV Light LED Method.

    pst...miter or tabel saw with 10inch 80 tooth $25 buck blade from harbor freight. my 5400rpm compound miter blasts through 1/4 in plexi w/o a chip... only issue i have is ryobi cm saw doesnt get or stay square very well so for my current project i took the blae to a friends house cause he had a compadible dewalt table saw. saw was like 3xxx rpms and still very little a few chips to none at all

    uh in practice it would seem connecting a bunch in series and multiplying nominal FV is done all the time. esp if hooked to a cc/cv dc-dc converter. Pull the light strip off a dead lcd once (make sure its not old ccfl style )

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  • JohnathanW15 commented on fozzy13's instructable NiChrome Hot Wire Cutter for Acrylic1 month ago
    NiChrome Hot Wire Cutter for Acrylic

    do you find this accurate enough to knotch a usb sized hole at an arbitrary place and have a nice square ish cut?

    I doubt you could at 2am on a work night in a large apartment complex... at least from the comfort of your desk/work bench in the unit. ie the hot knife wont disturb the neighbors like a rickety desk transfering the momentum of your saw into the floor. It also doesnt require clamping each piece

    google "how to use a search engine" , then go from there.

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  • RFID Reader Detector and Tilt-Sensitive RFID Tag

    if you still have this/ever try it again.... I think non conducting tape over the first layer except for one little edge then another layer of coper joined to that exposed tap and laid over the insulator layer (connected spiral of copper tape > insulator tape) vertically would work a bit better. dont bother with inward spiral as author of tutorial showed. The coils in the devices are usually vertical stacks. If you do EE stuff semi regularly you should pick up a roll of whats called "kapton tape" insulates and can with stand the heat of a soldering iron(like under the copper tape...solder doesnt actually stick to it.) If you have ever seen the transparent yellow orange tape on a lipo pack or inside electronics you probably respect this adhesive already, every time i see it ...see more »if you still have this/ever try it again.... I think non conducting tape over the first layer except for one little edge then another layer of coper joined to that exposed tap and laid over the insulator layer (connected spiral of copper tape > insulator tape) vertically would work a bit better. dont bother with inward spiral as author of tutorial showed. The coils in the devices are usually vertical stacks. If you do EE stuff semi regularly you should pick up a roll of whats called "kapton tape" insulates and can with stand the heat of a soldering iron(like under the copper tape...solder doesnt actually stick to it.) If you have ever seen the transparent yellow orange tape on a lipo pack or inside electronics you probably respect this adhesive already, every time i see it (even in old devices) it looks new and is still stuck where it should be. Nasa likes it as well if that means anything.

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  • JohnathanW15 commented on jts3k's instructable Controlling solenoids with arduino4 months ago
    Controlling solenoids with arduino

    use a "logic level mosfet" they come in N and P variety. N turns on when the gate pin is driven high, p turns on when get is grounded. you can also use p channels as reverse polarity safety devices on stuff you build and frequently connect/disconect power wire... if you tie the gate pin to ground then connect positive through the remaining terminals... the switch will be off if positive gets connected where ground is supposed to be on your power in. ;)

    i forgot to mention, after checking a mosfet can handle the volts and amps you need, look for RDS on value... that is the resistance through the part when the "switch" is on. n channel is lower but p channel is easier to use and still very reasonably low.

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  • JohnathanW15 commented on jts3k's instructable Controlling solenoids with arduino4 months ago
    Controlling solenoids with arduino

    its 2017, use a n or p channel mosfet

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  • Stop using Ferric Chloride etchant!  (A better etching solution.)

    that dude is one hell of a buzz kill. thanks for the great tutorial

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  • ATX to Lab Bench Power Supply Conversion

    Matthew, have you been on ebay recently? CC/CV boards cost 5 bucks for a stated 5 amp boost or buck...reality is 2-2.5amps unless you put some metal fins or odd chunk laying around on them. .One can get a Poly fuse multi value kit for dirt cheap as well. need more amps? If they have roughly double the budget have them search ebay for ltc3780. 10-12 bucks and a month wait to get one from china using an IC from Linear Tech in Cali. or you can get a board from an american based ebay shop in a week for about 23 bucks.worth noting:its auto regulating boost buck...the chip itself can do just about any form of power converter by re configuring (sepic, cuk etc ) I know all this because im prototyping a product and also keep a bunch of those cheap no name Dc-DC converters on hand for what ever ...see more »Matthew, have you been on ebay recently? CC/CV boards cost 5 bucks for a stated 5 amp boost or buck...reality is 2-2.5amps unless you put some metal fins or odd chunk laying around on them. .One can get a Poly fuse multi value kit for dirt cheap as well. need more amps? If they have roughly double the budget have them search ebay for ltc3780. 10-12 bucks and a month wait to get one from china using an IC from Linear Tech in Cali. or you can get a board from an american based ebay shop in a week for about 23 bucks.worth noting:its auto regulating boost buck...the chip itself can do just about any form of power converter by re configuring (sepic, cuk etc ) I know all this because im prototyping a product and also keep a bunch of those cheap no name Dc-DC converters on hand for what ever comes up I got my first 2 3780s for free but I didnt pay attention to the fact that the package was designed in imperial and ebay sop to dips apear to only be made in the 2 common metric pitches. I found one company that wanted like 12 bucks for the damn break out... so i paid the 23 to get the damn premade board asap and I will have 2 chips once I etch the second version at home.

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  • Uninterruptible Power Supply - Extending the Run Time

    i think you are better off having an electrician install romex(house mains wire) and extending the AC output than separating the bat from the invert er by a great distance. your resistance losses will succccck the battery dry and wire will get hot. wouldnt you rather that power went to your devices than heat?

    get yourself 3 solid state (normal will work but these SS is faster). Two should trigger with 120ac, the other ideally triggers at your MCUs 3.3 or 5v. on the other side of the mains triggered device, go from Vcc on your micro through a current limiting resister, to the other side of the relay back to a GPIO configured for input. Now you can loop and watch for it to go low. When it does go low raise another pin high, this will trigger the series configuration of the batteries to connect. With solid state relays it should happen faster than your gear turns off. for the P charging config use 2 standard coil based relays on one bat and join the charging sets (+ and - from both)after installing the relays mid line/before they join on one set of leads.... you only need to disconnect one batt...see more »get yourself 3 solid state (normal will work but these SS is faster). Two should trigger with 120ac, the other ideally triggers at your MCUs 3.3 or 5v. on the other side of the mains triggered device, go from Vcc on your micro through a current limiting resister, to the other side of the relay back to a GPIO configured for input. Now you can loop and watch for it to go low. When it does go low raise another pin high, this will trigger the series configuration of the batteries to connect. With solid state relays it should happen faster than your gear turns off. for the P charging config use 2 standard coil based relays on one bat and join the charging sets (+ and - from both)after installing the relays mid line/before they join on one set of leads.... you only need to disconnect one battery on both positive and negative (you dont need 4 if you think it through). These should trigger at the 3.3 or 5 of your mcu/micro and be high when wall power relay loop/signal is high is there low when wall signal goes low.

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  • ATX to Lab Bench Power Supply Conversion

    have you ever attempted to count the little lines that make up the digits in your "cheap 3 digit voltage meter"... u might find that there are 7, matt wasnt wrong calling it a segment display. Next time try to understand some people know more than you...trust me when I say it takes a lot of effort to find something to like about your build but he did and yet, you give additude in return

    I would bet one could take the "black magic" out of it if they read the markings on the DC-DC converters and used google to find the data sheets.

    nice dmm, u an eev blog fan? if you havent heard of it check it out. I ask because your choice in meter is one of his recomended ones

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