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  • sjowett commented on sjowett's instructable Mega Torch - the ultimate guide12 hours ago
    Mega Torch - the ultimate guide

    .......I've also edited the step about the power supply extolling the virtues of CC driving of LED's and the true wickedness of EVER having the temerity to suggest only controlling the voltage is satisfactory. It is NOT. (now sitting on the naughty stair in shame)

    .......I've also edited the step about the power supply extolling the virtues of CC driving of LED's and the true wickedness of NEVER EVER having the temerity to suggest only controlling the voltage is satisfactory. It is NOT (now sitting on the naughty stair in shame)

    Constant current is the way to go.......no doubt - see the reply given above for a recommendation.As for me I'm destined to get burned so this will be my last instructable.

    .... I've also edited the step regarding the power supply and hopefully extolling the virtues of CC driving and I give my sincere aploogies for having the temerity to suggest that you can satisfactorily drive an LED with a constant voltage source. You can NOT (now sitting on the naughty stair).

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  • sjowett made the instructable Mega Torch - the ultimate guide1 day ago
    Mega Torch - the ultimate guide

    I've added a couple of images grabs from 2 LED specification sheets. The one for the 100W LED is similar to the one I used in this project.The Voltage Vs Current 'curve' is nearly linear under the rated Vf. Your statement that an LED is somehow like a sticking check valve is odd given the data contained here - perhaps you can show data for the type of LED behaves in the way you described?Where you are correct is that once you exceed the rated Vf of an LED you quickly run into issues with excessive (current and resulting heat), but this is irrelevant to this project as I am well under this rated Vf.(35V). You may argue that there is a failure mode of the constant voltage DC-DC converter I used leading to uncontrolled voltage but I counter that by saying any current control DC-DC conv...see more »I've added a couple of images grabs from 2 LED specification sheets. The one for the 100W LED is similar to the one I used in this project.The Voltage Vs Current 'curve' is nearly linear under the rated Vf. Your statement that an LED is somehow like a sticking check valve is odd given the data contained here - perhaps you can show data for the type of LED behaves in the way you described?Where you are correct is that once you exceed the rated Vf of an LED you quickly run into issues with excessive (current and resulting heat), but this is irrelevant to this project as I am well under this rated Vf.(35V). You may argue that there is a failure mode of the constant voltage DC-DC converter I used leading to uncontrolled voltage but I counter that by saying any current control DC-DC converter will have similar failure mode issues. The worst that would happen is I blow up a $10 LED.Also, it may be easy to control a 20mA 'single' LED with a resistor but this type of current control would be disastrous for this project......for example, with a current 3A and a supply voltage of 40V.......this would need a 1.8Ohm resistor which would be dissipating over 16W!

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  • sjowett made the instructable Mega Torch - the ultimate guide1 day ago
    Mega Torch - the ultimate guide

    "Under driving them", below Vf, they do little or nothing. If you're making them light up, you are driving them at Vf. Both these statements are not correct - the luminosity is nearly linear to the current (see attached datasheets below). This is demonstrated in the videos as the voltage rises so does the current (and so does the luminosity of the LED).FYI one of the datasheets is for a 100W led similar to that used in this project and the other is fro a "plain vanilla" 5mm LED. In both cases the characteristic curves are similar.

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  • sjowett made the instructable Mega Torch - the ultimate guide5 days ago
    Mega Torch - the ultimate guide

    I guess we are getting a bit off topic but diodes require the 'extra' refinement in terminology to discriminate between forward voltage and reverse voltage as they are both critical parameters whenever you choose one for your circuit, (see spec sheet below).At least we (engineers) don't then give it a Latin name to obfuscate like the medico's!

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  • sjowett's instructable Mega Torch - the ultimate guide's weekly stats: 6 days ago
    • Mega Torch - the ultimate guide
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  • sjowett commented on sjowett's instructable Mega Torch - the ultimate guide6 days ago
    Mega Torch - the ultimate guide

    There seems to be some confusion here. A 3s LiPo battery will not even light the type of LED used in this project (100W led with a rated forward voltage of 35v). There is simply not enough voltage to get the semiconductor to conduct. If you watch my detailed video on step 2 you will see the LED's begin to illuminate at around 25V, and without controlling the current it is perfectly safe to ramp up the voltage to around 29V .....without any current control. At the same time if you want to run this LED at 35v then YES you are right you must control the current.

    I'm sorry I can't help as this instructable is predominantly based around detailed videos loaded up to YouTube (rather than my previous instructables which are predominantly picture based).

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  • sjowett commented on sjowett's instructable Mega Torch - the ultimate guide1 week ago
    Mega Torch - the ultimate guide

    Forward Voltage (Vf) is a term used on an LED's data sheet and refers to the voltage dropped across the LED while it is illuminated at the specified current etc. Effectively in my case this is the voltage provided by the DC-DC converter. You need to avoid going over this voltage as you will burn out the LED - Very quickly!

    Step 2 gives a fully detailed parts lists with links!

    yep! - Heat is the enemy of long life for LED's - thanks for the positive feedback Harry.

    Ha Ha - sorry GTO3x2! TonySuffolk has hit the nail on the head - I was born and brought up in the UK.... Celebrate the differences!

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  • sjowett commented on sjowett's instructable Mega Torch - the ultimate guide1 week ago
    Mega Torch - the ultimate guide

    The LED used is a 100w led made up of a matrix of 10x10 1w LED's. As such I had no choice of LED arrangement in this design. Similar LED's of 20W and 50W also have a 10 in series arrangement ie 2 x 10 and 5 x 10 respectively.

    ??ugh??

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  • sjowett commented on sjowett's instructable Mega Torch - the Ultimate Guide1 week ago
    Mega Torch - the Ultimate Guide

    Thanks for your comments. Yes - on the whole using a LED driver with a constant current control is a good thing. At the same time in this instance I am under driving the 100W LED. 'White' LED's of this type are actually blue LED's under a phosphor coating with a forward voltage of ~3.5v each. So with a 100W LED (with 10xLED's in series) this gives a full forward voltage of 35V. My battery voltage of 24V requires boosting and I limited the boost to well under 35V - (I also checked the current & power going to the LED to check this was true).However - as an alternative how about this board? www.ebay.com.au/itm/DC-DC-boost-converter-Constant-Current-Mobile-Power-supply-10A-250W-LED-Driver-/401033419926?txnId=598112995027I did have one of these but I let the magic smoke out!

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  • sjowett commented on sjowett's instructable Washing machine countdown timer - Arduino1 month ago
    Washing machine countdown timer - Arduino

    No issues - it still works fine.millis() is fine for this project as you can count down/up for around 50 days. millis() is an unsigned long variable and can there for count to over 4 billion (to be exact 0 to 4,294,967,295 (2^32 - 1))!

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  • sjowett commented on sjowett's instructable How to 'bling' up a boring staircase1 month ago
    How to 'bling' up a boring staircase

    The led that blinks 3 times is probably the LED attached to pin 13. My program gets his to flash 3 times when one of the PIRs has triggered. Have you checked the Arduino serial window? My code prints the LDR value and then "Detected Top" or "Detected bottom", this will correspond with the led flashing 3x alsoI can't emphasize enough that to isolate an issue its best to use a example program which focuses on the element you need to resolve. You can then build things back up

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  • sjowett commented on sjowett's instructable How to 'bling' up a boring staircase1 month ago
    How to 'bling' up a boring staircase

    Try the PIR in a little example program on it's own to try isolate the issue...Try this one for size?http://playground.arduino.cc/Code/PIRsense

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  • sjowett completed the lesson Welcome to CNC in the class CNC Class3 months ago
  • sjowett commented on sjowett's instructable RetroPie Arcade Cabinet (Cocktail Style)4 months ago
    RetroPie Arcade Cabinet (Cocktail Style)

    Not much at all really - there would be no need to rotate the screen (in the boot config.txt file) as I assume you would use it in 'normal' landscape mode. With many arcade games there is a 'in game' menu that is accessed by using a keyboard and hiting the "Tab" key after the game has started. In this menu you may find a "Upright or Cocktail" setting which you need to choose the first time you run that game.That's it -can't think of anything more of hand!Simon

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  • sjowett commented on sjowett's instructable RetroPie Arcade Cabinet (Cocktail Style)5 months ago
    RetroPie Arcade Cabinet (Cocktail Style)

    Hi TonyI've added a picture which should help. I'm assuming in my answer that you will be using the monitor in the landscape format not portrait as I have with the dell 17". Anyway, the width is about 370mm but don't forget the timbers taper in at 5 degrees. So, both the 24" (definitely) and hopefully the 26" would fit in. The larger monitor would be a very tight fit though. As for the length dimension the hinges take up about 70mm in from one end of the cabinet, if you centralize the monitor then you'd be taking 2 x 70mm from the interior length (which is 660). 660-140=520mm hmm this means that even the smaller monitor is going to be a squeeze, possible best to just make the cabinet sides a bit longer.Another thing to consider is the location of the Raspberry Pi a...see more »Hi TonyI've added a picture which should help. I'm assuming in my answer that you will be using the monitor in the landscape format not portrait as I have with the dell 17". Anyway, the width is about 370mm but don't forget the timbers taper in at 5 degrees. So, both the 24" (definitely) and hopefully the 26" would fit in. The larger monitor would be a very tight fit though. As for the length dimension the hinges take up about 70mm in from one end of the cabinet, if you centralize the monitor then you'd be taking 2 x 70mm from the interior length (which is 660). 660-140=520mm hmm this means that even the smaller monitor is going to be a squeeze, possible best to just make the cabinet sides a bit longer.Another thing to consider is the location of the Raspberry Pi and how close it is the the back of the monitor, although this is easy to overcome by placing the platform a bit lower.All the bestSimon

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  • sjowett commented on sjowett's instructable RetroPie Arcade Cabinet (Cocktail Style)5 months ago
    RetroPie Arcade Cabinet (Cocktail Style)

    I've update the step to reflect this - the finding and loading of the roms is definately the most challenging to get right!!!!

    Try putting the roms in the "Arcade" folder.

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  • sjowett commented on sjowett's instructable RetroPie Arcade Cabinet (Cocktail Style)5 months ago
    RetroPie Arcade Cabinet (Cocktail Style)

    I don't think so, the RetroPie and the various emulations seem to be configurable for resolution (if need be). However, I did not have to make any adjustments for the games I've tried to date.

    Hi Jo1) 4:3 it is from an old Dell 17" monitor2) The screen orientation change is set up in each game rom you load up. Once the game has loaded, (using a keyboard) you hit the "Tab" key and this brings up an 'in game' menu. Here you can set a number of parameters (or dip switches, this is a reference to the original set-up where individual micro switches inside the machine could change parameters). One of the parameters you can set is "upright" or "cocktail". This data seems to save ok between boots so you shouldn't need the keyboard connected permanently.Simon

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  • sjowett commented on sjowett's instructable RetroPie Arcade Cabinet (Cocktail Style)5 months ago
    RetroPie Arcade Cabinet (Cocktail Style)

    I think the Pi 3 should be ok for most early games. Of course as you move into the more highly rendered 3D games I'm guessing a PC with a dedicated video card may be required. I hope your build goes well!Simon

    Thanks so much, my next project is ......hmmmmm

    Thanks so much for the feedback....as for a drink holder, absolutely!

    Good idea Chris - it too makes me nervous when the lid is up! I would have preferred a 3rd glass clip at the hinge end also. Now the project is finished I guess the need to be inside the machine is much less. With a WiFi dongle you can load games onto the Pi without accessing the inside - perhaps I'll add another step!!!

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  • sjowett commented on sjowett's instructable RetroPie Arcade Cabinet (Cocktail Style)5 months ago
    RetroPie Arcade Cabinet (Cocktail Style)

    next week I think. Game on!

    Yes, I used a Pi 2 which I already had on hand. If buying new I'd definitely go for a Pi 3 as the price is now the same as the older model. Also, the ControlBlock is such a good and seamless integration I've got to recommend that also. The result is a much smaller physical and power footprint.

    Thanks - much appreciated!

    ...Glad you like it!

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  • sjowett commented on sjowett's instructable RetroPie Arcade Cabinet (Cocktail Style)5 months ago
    RetroPie Arcade Cabinet (Cocktail Style)

    Thanks for the positive feedback PeterCheersSimon

    Hi mstone25 - yes full details on step 3. Its not a cheap build but you could do something similar for a fraction of the costs Incurred. For a budget build you would forget the "T" moulding, leave out the glass top and perhaps the artwork could be hand drawn (but not by me I have no talents in that department)!CheersSimon

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  • Capacitive Discharge (CD) Welder for battery tabs

    Ok I've updated the instructable and added a number of new steps covering the circuit. I hope this helps!

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  • Capacitive Discharge (CD) Welder for battery tabs

    I'll look inside my welder this weekend and take some more photos and jot down some details to see if I can help.

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  • Capacitive Discharge (CD) Welder for battery tabs

    Wow that was sophisticated for the time! ...as for a welding voltage of 100-400v!!!You might be interested in this great resource for electronic spot weldinghttps://endless-sphere.com/forums/viewtopic.php?f=...There are loads of useful links on the first page of this forum post.

    The connections on the LCD end can be confusing as it depends on how the manufacturer has labeled the PCB - google search for st7920 images and you will see what I mean.To solve this 'off line' Id suggest just loading up the u8glib example to your Arduino and getting that working first. If you are still struggling then I can take a photo of my LCD but that means going under the lid and will take me a day or so too do.

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  • Capacitive Discharge (CD) Welder for battery tabs

    Yes - its a typo in the sense that I connected my screen with the 3 digital outputs 13, 11 and 12 (not 18, 16, 17 as the comment suggests). the line is a copy and paste from the u8glib example and I forgot to update the comment.

    There are some other basic versions out there using a car battery but with this method you can control the amount of energy closely by changing the charging voltage of the capacitors. The build is basically a copy of the equipment that the manufacturers use in commercial production.The value of the pots are not important. A linear (rather than a logarithmic) pot will give you better control. FYI I think I used a 10k pot.

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