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Gary_Gough

Make it yourself [DIYs & Modifications]

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Idea in progress .... feel free to make suggestions. My annual genocidal campaign on house flies has a new tool.

I was chasing flies off my computer screen last night and got to thinking about how annoying the things are. Every fall the house gets invaded by the things as they look for a place to spend the winter. While I can sympathize with the desire, that's not enough to dissuade me from plotting their death be it through direct violence, chemical warfare or traps. 

Fortunately for me insects are hard coded to do things that normally promote their odds of survival, and as a vindictive ape I can use that against them. 

Anyhow years ago in the early industrial age when we used incandescent lamps or gas mantle lamps, for short term bug traps we'd place a basin of sudsy water under a lamp and have the bugs fly over the light reflected from the bubbles and fly into the water. Not a bad trap but you need to froth it up every so often and it's kind of large. I want something I can setup and largely forget ( necessity doesn't hold a candle to laziness when it comes to invention ). So time to rethink. We now have LEDs , cool running, very efficient and small. So why not have the light come from under the water? 

Last night's experiment. Parts;

   a small glass bowl

   a few cm of white LED lighting strip

  water with a little dishwashing detergent.

I put the water in, wrapped the LEDs around the base of the bowl, and set it just under the computer monitor on my desk.

A few seconds after setting it up two flies dive bombed straight in... great sign :) , off to bed.... When I got called to work 6 hours later, there were 20 drowned flies and no obvious ones on the loose other then a couple at the base of the bowl right at the LEDs. So for round two I'm thinking of a cheap plastic tray, LEDs right under the middle and a black surround so all the light is coming from the water. Other option maybe a waterproof light right in the water and any old bowl.

The present 30 second hack actually makes a very nice night light so maybe I'll make it a permanent feature too. Maybe not the most optimal bug death trap, but visually appealing has it's points too.

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Update... Ok when I set that up I was hoping to reduce the fly numbers around my desk and keep them off my computer monitor. After two nights all the flies were cleared from 4 rooms and there were about 50 drowned ones in the bowl when I cleaned it out and re-filled. This is working so much better then I expected that I'm inclined to take up manufacturing.

DSC_0858sm.JPG

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Old knowledge, something that may not be getting passed along now...

I'm holding a collection of hard drive platters, intending to use one for a heat sink, and it dawned on me that the 2.5 " ones are near perfect signal mirrors ( roughly 1.5 cm central hole, two very good mirror surfaces and total weight around 1 gram ) followed by the thought " how many people would know how to use one?" So a mini course... Hold it up so the sun casts a shadow on you ( can practice with a house light ) the central hole will be a bright spot. While doing that look through the hole at the place you want the light to go. Move the disk until the reflection of the bright spot disappears in the center of the hole. You are now reflecting sun light directly at your intended target.  I know the new flashlights will do fine too, and this is a daylight only approach, but one more trick to have.

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A weird one I just learned:

A quick and dirty bulkhead fitting (sealable hole in a watertight container)  can be made with pvc conduit fittings, as these have straight vs. Tapered threads. Use male and female "threaded adapters"  and thick silicone o rings. Some silicone caulk too doesn't hurt.

I'm joining 5 gallon buckets for a hydroponics system.  The  "real" fittings cost 7-12 dollars us each. The conduit version is about $2 each. Be sure you use primer and cement if joining to schedule 40 pvc pipe.

Edited by Wyzyrd
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Battery backups.

Lots of us probably use UPSs for minor power drop outs, but for longer term they aren't great. Even with no load they are drawing enough to kill a lawn mower / golf cart battery in 8 to 10 hours. Also they tend to burn out their own charging circuit if you have a large dead lead acid battery on them ( like when the power comes back on ). Lots of the loads are 5 to 12 volts DC , so with a UPS you are charging a 12 volt battery from 120vAC , using it to make 120vAC stepping that down through a plug in adapter and then maybe drawing 60 MA at 5.5 volts at the far end ( real example from the base station on my cordless phone ).

Also all those free Li-Ion cells are piling up.

For $4 you can start with one of these.  https://www.aliexpress.com/item/6W-5V-UPS-mobile-power-Diy-Board-Charger-Step-up-DC-DC-Converter-Module-for-3/32790658678.html

It comes pre set to 5 volts out , but increasing the value of R1 lets you raise the output voltage from 5 to 12 volts. So as it sits it will run any USB powered devices and isn't a really tough hack to match it to other loads. Well ok, it takes soldering a surface mount resistor. Way to decide what value, there is .6 volts across R2 , and R1 forms a voltage divider with it, so 4.4 volt drop. once you have the resistor off, measure it, then divide 4.4 by it's value in ohms. That is how much current is going through the divider. Decide what voltage you want, subtract .6 , then multiply it by the current you calculated and pick the nearest resistor you have to that number.

The battery is a 3.6 V Li-Ion cell or pack. As a purely parallel pack there is no load balancing to worry about. You can make these as big as you want. But a few cautions. Avoid soldering to the negative end of Li-Ion cells, the positive end isn't as sensitive to heat so solder is ok there. You can buy 4 cell 18650 holders very cheap ( get the ones with each cell having it's own leads ) so might as well use those, side benefit it takes seconds to swap out 4 cells and get another week of use.   The really destructive thing with Li-Ion cells is reverse charging, which can happen if a higher voltage pack has a weak cell and then is over discharged . As a 3.6 volt pack, this can't happen so the only other issue is discharge below 3 volts will shorten the cells life.

One other option https://www.aliexpress.com/item/1PCS-DC-DC-Converter-SX1308-2A-Step-UP-Adjustable-Power-Module-Booster/32766867006.html

This is just a booster without a charger circuit , but $0.75 and you can dial up any voltage from about 5 volts to 28 volts. Good idea to put a battery protection circuit in if you intend to leave it unattended as it will keep going until the battery drops below 2 volts.

Anyhow now the "Why". Large lead acid battery compared to 4* 18650 cells. the small pack will run my cordless phone base ( and keep the phone charged ) for about 1 week of continuous use. The large lead acid is dead in 1/3 day.  Also the UPS has better uses supplying 120V where needed ( bench tools etc. ). For the price you can throw these things at all sorts of low voltage devices. Cordless phone repeater ( 6.5 volts at 100 MA ) Cell phone repeater/amp ( 5 volts at 2 amps ). Cell phone charging station/ USB charging ports. Laptop computers ( Lenovos are 20 volts, an S10 has a 2 amp power supply, a T520 has a 4.5 amp supply , so will need to get a larger rated booster. Remember if it's rated at 2 Amps that could well be the battery draw . 20 volts at 2 amps will be more like 12 amps at 3.6 volts, that $0.75 booster will melt ) If you are doing a laptop supply, run 4 packs in series, put a load balanced charger together and then boost it to 20 volts ( from about 14 volts, still a slight overload for the cheap booster, but it might just do it if you let the laptop charge for awhile before turning it on. ) . There is also nothing saying you can't put several loads onto the same battery bank with each regulated to the device voltage. So a 2 KWH ( about 400 18650 cells ) pack could run all your lighting, electronics  inc. a laptop for 4 days between charges, much more if you shut the large drain stuff off while you're sleeping and /or not using it. Can also use an inverter on a 14 volt system but they can use huge amounts of power ( 1,000 watt toaster oven will use 1/2 of the battery in an hour ) If you do go that large , fuse each cell individually ( 32 gauge wire from a buss bar to + on each cell should do ). Probably a better idea to cook with gas anyhow.

The efficiency is in the 95% range for the booster, so over all could be better then 75% for the full system as compared to nearly 0% for a lightly loaded UPS ( it gets better with  with short term larger loads but still not great ).

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On 29/08/2017 at 0:22 AM, Gary_Gough said:

Battery backups.

Lots of us probably use UPSs for minor power drop outs, but for longer term they aren't great. Even with no load they are drawing enough to kill a lawn mower / golf cart battery in 8 to 10 hours. Also they tend to burn out their own charging circuit if you have a large dead lead acid battery on them ( like when the power comes back on ). Lots of the loads are 5 to 12 volts DC , so with a UPS you are charging a 12 volt battery from 120vAC , using it to make 120vAC stepping that down through a plug in adapter and then maybe drawing 60 MA at 5.5 volts at the far end ( real example from the base station on my cordless phone ).

Also all those free Li-Ion cells are piling up.

For $4 you can start with one of these.  https://www.aliexpress.com/item/6W-5V-UPS-mobile-power-Diy-Board-Charger-Step-up-DC-DC-Converter-Module-for-3/32790658678.html

It comes pre set to 5 volts out , but increasing the value of R1 lets you raise the output voltage from 5 to 12 volts. So as it sits it will run any USB powered devices and isn't a really tough hack to match it to other loads. Well ok, it takes soldering a surface mount resistor. Way to decide what value, there is .6 volts across R2 , and R1 forms a voltage divider with it, so 4.4 volt drop. once you have the resistor off, measure it, then divide 4.4 by it's value in ohms. That is how much current is going through the divider. Decide what voltage you want, subtract .6 , then multiply it by the current you calculated and pick the nearest resistor you have to that number.

The battery is a 3.6 V Li-Ion cell or pack. As a purely parallel pack there is no load balancing to worry about. You can make these as big as you want. But a few cautions. Avoid soldering to the negative end of Li-Ion cells, the positive end isn't as sensitive to heat so solder is ok there. You can buy 4 cell 18650 holders very cheap ( get the ones with each cell having it's own leads ) so might as well use those, side benefit it takes seconds to swap out 4 cells and get another week of use.   The really destructive thing with Li-Ion cells is reverse charging, which can happen if a higher voltage pack has a weak cell and then is over discharged . As a 3.6 volt pack, this can't happen so the only other issue is discharge below 3 volts will shorten the cells life.

One other option https://www.aliexpress.com/item/1PCS-DC-DC-Converter-SX1308-2A-Step-UP-Adjustable-Power-Module-Booster/32766867006.html

This is just a booster without a charger circuit , but $0.75 and you can dial up any voltage from about 5 volts to 28 volts. Good idea to put a battery protection circuit in if you intend to leave it unattended as it will keep going until the battery drops below 2 volts.

Anyhow now the "Why". Large lead acid battery compared to 4* 18650 cells. the small pack will run my cordless phone base ( and keep the phone charged ) for about 1 week of continuous use. The large lead acid is dead in 1/3 day.  Also the UPS has better uses supplying 120V where needed ( bench tools etc. ). For the price you can throw these things at all sorts of low voltage devices. Cordless phone repeater ( 6.5 volts at 100 MA ) Cell phone repeater/amp ( 5 volts at 2 amps ). Cell phone charging station/ USB charging ports. Laptop computers ( Lenovos are 20 volts, an S10 has a 2 amp power supply, a T520 has a 4.5 amp supply , so will need to get a larger rated booster. Remember if it's rated at 2 Amps that could well be the battery draw . 20 volts at 2 amps will be more like 12 amps at 3.6 volts, that $0.75 booster will melt ) If you are doing a laptop supply, run 4 packs in series, put a load balanced charger together and then boost it to 20 volts ( from about 14 volts, still a slight overload for the cheap booster, but it might just do it if you let the laptop charge for awhile before turning it on. ) . There is also nothing saying you can't put several loads onto the same battery bank with each regulated to the device voltage. So a 2 KWH ( about 400 18650 cells ) pack could run all your lighting, electronics  inc. a laptop for 4 days between charges, much more if you shut the large drain stuff off while you're sleeping and /or not using it. Can also use an inverter on a 14 volt system but they can use huge amounts of power ( 1,000 watt toaster oven will use 1/2 of the battery in an hour ) If you do go that large , fuse each cell individually ( 32 gauge wire from a buss bar to + on each cell should do ). Probably a better idea to cook with gas anyhow.

The efficiency is in the 95% range for the booster, so over all could be better then 75% for the full system as compared to nearly 0% for a lightly loaded UPS ( it gets better with  with short term larger loads but still not great ).

All this tinkering with li-ion cells, do you ever worry about the potential for kaboom? I use IMR cells exclusively due to 1 bad experience with a cheap unprotected li-ion cell in the past. :/

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2 hours ago, Thomas said:

All this tinkering with li-ion cells, do you ever worry about the potential for kaboom? I use IMR cells exclusively due to 1 bad experience with a cheap unprotected li-ion cell in the past. :/

Always a concern with any batteries. The fact they store and release energy means they are potentially dangerous in proportion to how fast they can release energy, even if that is often a desirable trait. Historically, I had a NiCd pack short out while in my pocket, grabbed it and threw, then turned my motorcycle around and collected the pieces. A Li-Ion with no fuse running into a short can start fires, explode, and generally be messy. In series, if one cell is weak and the pack isn't protected and balanced, discharging can take that weak cell and reverse charge it. More then a few % and it's destroyed and maybe a hazard. Ripping apart laptop packs, as a rule they have their own microprocessor monitoring the voltage across each 3.6 volt section and if any one section drops below 3 volts the whole pack shuts off, they also have temperature sensors to shut down if going over safe temperature. Earlier packs had 109 degree thermal fuses, but those are often blown by being left in a hot vehicle so are much rarer now. I've seen a few packs with one section showing a reverse voltage ( generally in millivolts ) and those cells are shot. That's where a 3.6 volt pack has some good points, as it's all one parallel pack no part of it can ever be reverse charged by the rest, so just safe voltage limiting is easy. Using a fine wire fuse on each cell will stop any one bad cell from shorting out the full pack. The other major problem with Li-Ion is charging while cold ( say -20c ) The battery charges as a lithium metal battery, which has much higher storage density but tends to form internal metal bridges between plates. The bridge is a short, the cell discharges internally through that short and can create an even larger short followed by the unusual nasties. In normal use a Li-Ion doesn't out gas, so they are totally sealed ( with a safety vent to blow out if they are failing ) , a lead acid vents hydrogen in normal use so you can't really seal them. Most other cells have out gassing ( or in ) characteristics. A silver cell uses oxygen up as discharging.

If you look at the really big current draw uses, cars for instance, each cell will have it's own fuse , the whole set are often cooled, sometimes by liquid, ( or heated to above 4 C ) and have a major effort put into monitoring and balance control.

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Useful bits and pieces, while salvaging Li-Ion cells.IMG_3788cr.thumb.JPG.d5061059391e9c2275054b2431967262.JPGThis was an older Toshiba pack ,old enough that all 6 cells were totally shot. Still parts. The black rectangle is a self resetting circuit breaker ( also trips around 77C ) Great for protecting batteries and loads that are running unattended. Silver cylinder is a 99degree C thermal fuse with a 10 amp rating , so too hot or too much current ( and the breaker failing ) kills the pack for good, but before it is likely to catch fire. That brown tag connected to T1 and T2 is a thermistor to read temperatures. IC1 is a purpose made microprocessor , and IC2 is a common 4 K bit EEPROM with I2C communications. ( 512 byte ) I haven't dug any further and I'll assume IC2 just acts as scratchpad memory for the laptop to read and store battery information with a Micro monitoring voltages and temperature and reporting to the laptop. All useful stuff and other then the processor all reusable ( no docs for the MPU ) 

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8 hours ago, Gary_Gough said:

Useful bits and pieces, while salvaging Li-Ion cells.IMG_3788cr.thumb.JPG.d5061059391e9c2275054b2431967262.JPGThis was an older Toshiba pack ,old enough that all 6 cells were totally shot. Still parts. The black rectangle is a self resetting circuit breaker ( also trips around 77C ) Great for protecting batteries and loads that are running unattended. Silver cylinder is a 99degree C thermal fuse with a 10 amp rating , so too hot or too much current ( and the breaker failing ) kills the pack for good, but before it is likely to catch fire. That brown tag connected to T1 and T2 is a thermistor to read temperatures. IC1 is a purpose made microprocessor , and IC2 is a common 4 K bit EEPROM with I2C communications. ( 512 byte ) I haven't dug any further and I'll assume IC2 just acts as scratchpad memory for the laptop to read and store battery information with a Micro monitoring voltages and temperature and reporting to the laptop. All useful stuff and other then the processor all reusable ( no docs for the MPU ) 

interesting, whats your opinion on IMR cells? Is it really that much safer?

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1 hour ago, Thomas said:

interesting, whats your opinion on IMR cells? Is it really that much safer?

Double edged sword. I like them, lower internal resistance so safer on high current devices due to less heating. Down side is they will deliver even more power into a short. So do put a fuse in the load and be careful to avoid shorts.

If you are building power supplies to run unattended, these are a good idea. https://www.aliexpress.com/item/3-7V-4-2V-3A-Li-ion-Lithium-Battery-Charger-Over-Charge-Discharge-Overcurrent-Protection-Board/32803131082.html

If you want to know how healthy a cell is, and how safe, internal resistance is the way to go. Easy to measure with a fixed load ( say a 1 ohm resistor , 10 watt minimum as you can easily be running 4 watts through it, it will get hot ) and a volt meter. Measure the open voltage ( no load, I'll call this Vo ), put the load on and measure the voltage ( call that Vl ). Then plug the numbers into these. current (A)  = Vl/R , since R=1 that just means you can say the current in amps = the voltage under load. The voltage drop from open is caused by internal resistance, so Vo-Vl = the drop across the internal resistance ( I'll call that Vi ) so Vi/A = the internal resistance.  A high drain 18650 cell can be down around 15 milliohms , a run of the mill Li-ion maybe 70 milliohm , for context I've seen carbon zinc cells around an ohm.

The internal heating and safe discharge rate fall right out of that. As a battery ages it will rise. You'll also notice a cell that is going to over heat in a vape could be fine in a flash light. Also short duration loads can be fine as it takes a few seconds for heat to build up.

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On 2017/09/09 at 6:49 PM, Rspreps said:

Anyone else's head spinning? Gary, you are by far the closest thing to a human 'Google' I've ever (virtually) met! 

I'm just an old tech, maybe started a little earlier so I have had more time to learn from my mistakes.

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For anyone thinking about wind power, I've got a spreadsheet to play with, but it needs to be renamed from .doc to .ods ( well Libre Office is actually smart enough to open it with Libre Calc even miss named ).

The entered numbers are an example and based on an article I ran into. The nice thing about it being a spread sheet is you can punch in site numbers and get a good idea what to expect for outputs.

Libre Office is free ( as in beer ) but if anyone wants I can probably turn this into a XL spreadsheet , I just can't test it in that format.

windwork.doc

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Thanks :)

In libre office,  you just have to go to File -> Save As ,  then use the pulldown below filename to choose .ods, or .xls or .xlsx, or whatever you like. 

I'm cheap, never paid for ms office.. used Open Office until Oracle bought Sun, and the developers jumped ship to format Libre Office, which is what I use now :)

Libre Office will open all the ms formats too 

Edited by Wyzyrd
Hit save too fast

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Yeah, the open document formats aren't allowed to post so changing the extension to .doc was a work around. I keep recovering files for people using Microsoft programs when they do an "upgrade" and the new version refuses to open their old work ( retrieving stuff from MS Works is a pain but I think Microsoft has finished killing it ) but as I've said before "It was Vista that convinced me to try Linux and I've never had the courtesy to thank Microsoft." Never tried to recover any Lotus files ( Hmm remember when PC cards were "LIM" standard , Intel and Microsoft are still around but no more L ). Well power is out so I'd best cut this off while I still can save.

 

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On 10/09/2017 at 1:49 AM, Rspreps said:

Anyone else's head spinning? Gary, you are by far the closest thing to a human 'Google' I've ever (virtually) met! 

+1 literally. Whenever @Gary_Gough responds, I grab a cup of tea and make time so that I don't mentally implode. ;) 

Edited by Thomas
typotypotypo

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