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#1
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A wall-wart alternative
I finally got tired of replacing the 2 C-cells in a clock with a moving
pendulum, so I measured the current (3 volts at 340 microamps) and built a charge pump like this, viewed in a fixed font: 0.047 uF @400 V || | -----------||---------------------|------------ || | | | | | 3V 120 VAC --- --- to clock ^ _ 0.047 uF @400 V | | || | | -----------||----------------------------------- || I used two caps in case one shorts and for some ground isolation. The diodes are 5.1 V zeners ($1.29 for 2 at Radio Shack) to limit the clock voltage if someone unplugs the batteries. This circuit supplies 390 microamps. I hope to avoid replacing the batteries until their shelf life runs out in 2012 :-) This could be useful for lots of low-power stuff, eg smoke detectors. Nick |
#2
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A wall-wart alternative
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#3
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A wall-wart alternative
I used a ac adapter of the proper voltage to charge a bunch of D sixed
nicads to run my answering machine during power failures. it was like a UPS uninterruptiple power supply. my old machine would spaz with any power failure The batteries went bad after 6 years, my new machine a different voltage with a battery backup of memory, so I dont use this anymore |
#4
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A wall-wart alternative
I hope you are using rechargable batteries!
Regulart alkaline or others may dry out, overheat and start a fire! USE ONLY RECHARGABLE BATTERIES IN THIS APPLICATION! |
#5
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A wall-wart alternative
I like the concept, but it's hardly worth doing if you value the
portability of the object and batteries can be had so cheaply. |
#6
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A wall-wart alternative
wrote:
I hope you are using rechargable batteries! NO! Regulart alkaline or others may dry out, overheat and start a fire! How much will they overheat if overchaged at 3Vx50uA = 150 microwatts? :-) USE ONLY RECHARGABLE BATTERIES IN THIS APPLICATION! NO! Happy new year, Nick |
#7
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A wall-wart alternative
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#8
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A wall-wart alternative
Clark wrote:
Looks like a shock hazard to me. wrote in message oups.com... wrote: I finally got tired of replacing the 2 C-cells in a clock with a moving pendulum, so I measured the current (3 volts at 340 microamps) and built a charge pump like this, viewed in a fixed font: 0.047 uF @400 V || | -----------||---------------------|------------ || | | | | | 3V 120 VAC --- --- to clock ^ _ 0.047 uF @400 V | | || | | -----------||----------------------------------- || I used two caps in case one shorts and for some ground isolation. The diodes are 5.1 V zeners ($1.29 for 2 at Radio Shack) to limit the clock voltage if someone unplugs the batteries. This circuit supplies 390 microamps. I hope to avoid replacing the batteries until their shelf life runs out in 2012 :-) This could be useful for lots of low-power stuff, eg smoke detectors. Nick Caps do have a failure mode, so a series safety R is normally included with these type circuits. And at that low a current, why not ferget the caps and just use a couple of 150K resistors? The additional power loss will hardly spin your meter off the wall and you'll avoid the possible cap failure problem. Jeff (Ducking and slinking off...) -- Jeffry Wisnia (W1BSV + Brass Rat '57 EE) "Truth exists; only falsehood has to be invented." If your ac supply is polarised, you'd be a bit safer putting one cap in the live than one in each pole, as the output will then be at apx earth potential, though not isolated. As it stands its semi-live. NT |
#9
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A wall-wart alternative
I...built a charge pump like this, viewed in a fixed font:
0.047 uF @400 V || | -----------||---------------------|------------ || | | | | | 3V 120 VAC --- --- to clock ^ _ 0.047 uF @400 V | | || | | -----------||----------------------------------- || Nick (nicksanspam @ ece.villanova.edu) Caps do have a failure mode, so a series safety R is normally included with these type circuits. NT (meow2222 @ care2.com) It should be noted that such *series capacitor* devices were outlawed for commercial products long ago in Europe. As the Big Cat notes, without a resistor to limit things, failures are usually dramatic. |
#10
Posted to alt.home.repair,alt.energy.homepower,misc.consumers.frugal-living
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A wall-wart alternative
wrote in message ...
I finally got tired of replacing the 2 C-cells in a clock with a moving pendulum, so I measured the current (3 volts at 340 microamps) and built a charge pump like this, viewed in a fixed font: 0.047 uF @400 V || | -----------||---------------------|------------ || | | | | | 3V 120 VAC --- --- to clock ^ _ 0.047 uF @400 V | | || | | -----------||----------------------------------- || I used two caps in case one shorts and for some ground isolation. The diodes are 5.1 V zeners ($1.29 for 2 at Radio Shack) to limit the clock voltage if someone unplugs the batteries. This circuit supplies 390 microamps. I hope to avoid replacing the batteries until their shelf life runs out in 2012 :-) This could be useful for lots of low-power stuff, eg smoke detectors. Nick It seems counter-productive to build booby-traps into smoke detectors and the like. Unlike a wall-wart, it will require special precautions not to accidentally touch anything when you go to change the battery or maybe even set the time on a clock. You will never know whether a capacitor has shorted and whether you might be killed the next time you provide a path to earth ground. There's nothing to limit the current when capacitors fail, so that failure will cause a fire. There's no transient voltage protection, so the odds of capacitor over-voltage failure is pretty high. Don |
#11
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A wall-wart alternative
What is your child's life worth when they need to steal
a battery for their latest toy? That's just idiotic. "Al Bundy" wrote in message oups.com... I like the concept, but it's hardly worth doing if you value the portability of the object and batteries can be had so cheaply. |
#12
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A wall-wart alternative
2 Lithium batteries would be safer, cheaper, less work,
last longer and much more reliable. Just a moronic idea "JeffM" wrote in message oups.com... I...built a charge pump like this, viewed in a fixed font: 0.047 uF @400 V || | -----------||---------------------|------------ || | | | | | 3V 120 VAC --- --- to clock ^ _ 0.047 uF @400 V | | || | | -----------||----------------------------------- || Nick (nicksanspam @ ece.villanova.edu) Caps do have a failure mode, so a series safety R is normally included with these type circuits. NT (meow2222 @ care2.com) It should be noted that such *series capacitor* devices were outlawed for commercial products long ago in Europe. As the Big Cat notes, without a resistor to limit things, failures are usually dramatic. |
#13
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A wall-wart alternative
Don K wrote:
wrote: 0.047 uF @400 V 1K || | ----www----||---------------------|------------ || | | | | | 3V 120 VAC --- --- to clock ^ _ 0.047 uF @400 V | | || | | -----------||----------------------------------- || Unlike a wall-wart, it will require special precautions not to accidentally touch anything when you go to change the battery... And it has battery backup :-) There's nothing to limit the current when capacitors fail, so that failure will cause a fire. I doubt that. The diodes will probably open, and I used really skinny wire. There's no transient voltage protection, so the odds of capacitor over-voltage failure is pretty high. Or diode damage. So... I added a 1K series resistor. This would also work: 0.022 uF @400 V* || | -----------||---------------------|------------ || | | | | | 3V 120 VAC --- --- to clock ^ _ | | 10K | | -----------www---------------------------------- *Digikey's $29.95 M400-KIT-ND 400 V capacitor assortment contains 10 of these, along with 10 of 14 other values from 0.001 to 0.1 uF. Nick |
#14
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#15
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#16
Posted to alt.home.repair,alt.energy.homepower,misc.consumers.frugal-living
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A wall-wart alternative
0.022 uF @400 V*
|| | -----------||---------------------|------------ || | | | | | 3V 120 VAC --- --- to clock ^ _ | | 10K | | -----------www---------------------------------- *Digikey's $29.95 M400-KIT-ND 400 V capacitor assortment contains 10 of these, along with 10 of 14 other values from 0.001 to 0.1 uF. The rest of this stuff is cheap... $13.65 for 100 1N5231BD1CTND 5.1V zeners, $15.86 for 1000 P10KBACTND 10K resistors, and a line cord cut off an old appliance. Anyone else want to burn their house down? :-) Nick |
#17
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A wall-wart alternative
nick pine wrote:
0.022 uF @400 V* || | -----------||---------------------|------------ || | | | | | 3V 120 VAC --- --- to clock ^ _ | | 10K | | -----------www---------------------------------- *Digikey's $29.95 M400-KIT-ND 400 V capacitor assortment contains 10 of these, along with 10 of 14 other values from 0.001 to 0.1 uF. The rest of this trickle charger is cheap... $13.65 for 100 1N5231BD1CTND 5.1V zeners, $15.86 for 1000 P10KBACTND 10K resistors, and a line cord cut off an old appliance. My smoke detector draws 7 uA = 60x370C, which makes C = 315 puffs, eg 2 0.001 uF 400 V caps in series, Digikey's P1058-ND, $11.43/100. They also sell 12 V zeners suitable for 9 V batteries, 1N5242BDICT-ND, $13.65/100. Nick |
#18
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A wall-wart alternative
wrote in message ... nick pine wrote: 0.022 uF @400 V* || | -----------||---------------------|------------ || | | | | | 3V 120 VAC --- --- to clock ^ _ | | 10K | | -----------www---------------------------------- *Digikey's $29.95 M400-KIT-ND 400 V capacitor assortment contains 10 of these, along with 10 of 14 other values from 0.001 to 0.1 uF. The rest of this trickle charger is cheap... $13.65 for 100 1N5231BD1CTND 5.1V zeners, $15.86 for 1000 P10KBACTND 10K resistors, and a line cord cut off an old appliance. My smoke detector draws 7 uA = 60x370C, which makes C = 315 puffs, eg 2 0.001 uF 400 V caps in series, Digikey's P1058-ND, $11.43/100. They also sell 12 V zeners suitable for 9 V batteries, 1N5242BDICT-ND, $13.65/100. Nick Of course you don't have enough current for the audible device so your smoke detector should sit quietly by while you toast! |
#19
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#20
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A wall-wart alternative
Bill_M wrote:
0.001 0.001 uF @400 V* || || | ----||-----||---------------------|------------ || || | | | | | 9V 120 VAC --- --- to smoke detector ^ _ | | 10K | | -----------www---------------------------------- My smoke detector draws 7 uA = 60Hzx2xsqrt(2)x120VxC, which makes C = 344 pF, eg 2 0.001 uF 400 V caps in series, Digikey's P1058-ND, $11.43/100. They also sell 12 V zeners suitable for 9 V batteries, 1N5242BDICT-ND, $13.65/100. Of course you don't have enough current for the audible device so your smoke detector should sit quietly by while you toast! No. That current would come from the 9 V trickle-charged battery. We might replace it every 6 years or so, if the alarm fails to shriek with the test button. Nick |
#21
Posted to alt.home.repair,alt.energy.homepower,misc.consumers.frugal-living
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A wall-wart alternative
wrote in message oups.com...
wrote: Don K wrote: wrote: There's nothing to limit the current when capacitors fail, so that failure will cause a fire. X rated capacitors use fusible coatings, so a short causes a burn out of the conductor around the short. The overall capacitance is not noticeably affectde, IOW its self healing. I doubt that. The diodes will probably open, and I used really skinny wire. Very fine wire sounds like effective fusing to me. You only need 20mA of AC current to cause ventricular fibrillation. If the capacitor fails, someone could get killed touching whatever your circuit connects to. Don |
#22
Posted to alt.home.repair,alt.energy.homepower,misc.consumers.frugal-living
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A wall-wart alternative
0.0047 uF @400 V*
|| | -----------||---------------------|------------ || | | | | | 1.5V 120 VAC --- --- to clock ^ _ | | 10K | | -----------www---------------------------------- can trickle-charge a Seth Thomas quartz clock with hands and a AA battery ("Replace every 12 months or in case of suddenly inaccurate timekeeping.") The trickle-charged battery might last 10 years. The battery current jumps when the second hand ticks, but a 1K resistor and a 10K microfarad smoothing capacitor reveal an average 95 microamps = 60Hzx2xsqrt(2)x120VxC, which makes C = 0.0047 uF, one of the 150 caps in Digikey's $29.95 M400-KIT-ND. Their P10KBACT-ND 10K resistors cost $15.86/1000... 1N5231BD1CTND 5.1V zener diodes cost $13.65/100. Their number is 1-800-344-4539. Most orders are shipped in 12-14 minutes. This circuit uses about 1.5Vx95uA = 142 microwatts, ie 1.2 Wh/year worth $0.000125 at 10 cents/kWh. It's probably illegal. Don't try this at home. Nick |
#23
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A wall-wart alternative
wrote:
My smoke detector draws 7 uA = 60x370C, which makes C = 315 puffs, eg 2 0.001 uF 400 V caps in series, Digikey's P1058-ND, $11.43/100. They also sell 12 V zeners suitable for 9 V batteries, 1N5242BDICT-ND, $13.65/100. You have to supply bleeping power, relying on the battery would be unsatisfactory. In which case it'll draw bleeping power al the time, Only with constant house fires. Nick |
#24
Posted to alt.home.repair,alt.energy.homepower,misc.consumers.frugal-living
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A wall-wart alternative
Don K wrote:
wrote in message oups.com... wrote: Don K wrote: wrote: There's nothing to limit the current when capacitors fail, so that failure will cause a fire. X rated capacitors use fusible coatings, so a short causes a burn out of the conductor around the short. The overall capacitance is not noticeably affectde, IOW its self healing. I doubt that. The diodes will probably open, and I used really skinny wire. Very fine wire sounds like effective fusing to me. You only need 20mA of AC current to cause ventricular fibrillation. If the capacitor fails, someone could get killed touching whatever your circuit connects to. Don It would be a foolish designer that enabled users to touch the output of one of these, so thats a non issue in a competent design. If for some reason they did, Y rated caps would be more appropriate than X - but still, liability like that isnt something I'd want to take on unnecessarily. As far as fusing, if a cap shorts, enough i will flow to pop a fine wire, assuming it really is fine. A single strand of a thin stranded equipment wire etc. So the fuse concept is good. I suppose if one wanted to improve the safety of an unsafe device (ie nonisolated supply with outputs touchable) one could put a cap in both poles and earth the supply output. Would need to ensure R is significant to avoid RCD problems. Note this would work as a 1 cap supply, as the E connection would effectively short out the neutral capacitor. Ick. NT |
#25
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A wall-wart alternative
Don K wrote:
wrote in message oups.com... wrote: Don K wrote: wrote: There's nothing to limit the current when capacitors fail, so that failure will cause a fire. X rated capacitors use fusible coatings, so a short causes a burn out of the conductor around the short. The overall capacitance is not noticeably affectde, IOW its self healing. I doubt that. The diodes will probably open, and I used really skinny wire. Very fine wire sounds like effective fusing to me. You only need 20mA of AC current to cause ventricular fibrillation. If the capacitor fails, someone could get killed touching whatever your circuit connects to. Don It would be a foolish designer that enabled users to touch the output of one of these, so thats a non issue in a competent design. If for some reason they did, Y rated caps would be more appropriate than X - but still, liability like that isnt something I'd want to take on unnecessarily. As far as fusing, if a cap shorts, enough i will flow to pop a fine wire, assuming it really is fine. A single strand of a thin stranded equipment wire etc. So the fuse concept is good. I suppose if one wanted to improve the safety of an unsafe device (ie nonisolated supply with outputs touchable) one could put a cap in both poles and earth the supply output. Would need to ensure R is significant to avoid RCD problems. NT |
#26
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#27
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#28
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A wall-wart alternative
phatty mo wrote:
Why not a small dc-dc converter,from your main 12/24/48V battery bank.. I don't have a battery bank. Safer,and probably more efficient. (takes the inverter out of the loop,atleast.) If your main inverter doesn't run 100% of the time, you might make the cap larger to charge the battery more when the inverter does run. This circuit itself is unlikely to make the inverter come out of hibernation. Nick |
#29
Posted to alt.home.repair,alt.energy.homepower,misc.consumers.frugal-living
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A wall-wart alternative
These "hot" circuits were always accompanied by safety
devices that disabled them from human contact. eg. - polarized plugs - cheater cords that disconnected when the back was removed - all plastic insulated knobs to avoid metal exposure. wrote in message ... 0.0047 uF @400 V* || | -----------||---------------------|------------ || | | | | | 1.5V 120 VAC --- --- to clock ^ _ | | 10K | | -----------www---------------------------------- can trickle-charge a Seth Thomas quartz clock with hands and a AA battery ("Replace every 12 months or in case of suddenly inaccurate timekeeping.") The trickle-charged battery might last 10 years. The battery current jumps when the second hand ticks, but a 1K resistor and a 10K microfarad smoothing capacitor reveal an average 95 microamps = 60Hzx2xsqrt(2)x120VxC, which makes C = 0.0047 uF, one of the 150 caps in Digikey's $29.95 M400-KIT-ND. Their P10KBACT-ND 10K resistors cost $15.86/1000... 1N5231BD1CTND 5.1V zener diodes cost $13.65/100. Their number is 1-800-344-4539. Most orders are shipped in 12-14 minutes. This circuit uses about 1.5Vx95uA = 142 microwatts, ie 1.2 Wh/year worth $0.000125 at 10 cents/kWh. It's probably illegal. Don't try this at home. Nick |
#30
Posted to alt.home.repair,alt.energy.homepower,misc.consumers.frugal-living
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A wall-wart alternative
****. get a small flexible PV panel and use the damn
thing. wrote in message ... phatty mo wrote: Why not a small dc-dc converter,from your main 12/24/48V battery bank.. I don't have a battery bank. Safer,and probably more efficient. (takes the inverter out of the loop,atleast.) If your main inverter doesn't run 100% of the time, you might make the cap larger to charge the battery more when the inverter does run. This circuit itself is unlikely to make the inverter come out of hibernation. Nick |
#31
Posted to alt.home.repair,alt.energy.homepower,misc.consumers.frugal-living
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A wall-wart alternative
SolarFlare wrote:
get a small flexible PV panel glue it to the face of the clock add a series resistor and schottky diode to charge the battery. the frugal will steal the parts from a defunct solar calculator ;-) Nick, put equal value cap and resistor in series with each line and your diodes in a small box with ac plug (gutted wall wart- there's justice?) then run small cable (like the old earphone cable) up to clock. Paint red insulator over any "hot" parts in clock. The "power" cable will be about as dangerous as any current small appliance "leakage" since most have .045 mF caps from EACH power lead to chassis. UL specifies an allowable leakage level. 5 ma sounds familiar since that's the level that GFI's are supposed to trip at. There's a thought, wire it any way you want to, then plug it into a gfi ;-) hook all your clocks, smoke detectors, etc together and use just one gfi. the gfi will use more power than you're saving. have a good new year -larry / dallas |
#32
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A wall-wart alternative
Get an old coil for induction and put a series diode to
the battery. Hang it someplace over wiring with a good load feed. voila...self contained clock with no dangerous connection to high voltage. "larry" wrote in message et... SolarFlare wrote: get a small flexible PV panel glue it to the face of the clock add a series resistor and schottky diode to charge the battery. the frugal will steal the parts from a defunct solar calculator ;-) Nick, put equal value cap and resistor in series with each line and your diodes in a small box with ac plug (gutted wall wart- there's justice?) then run small cable (like the old earphone cable) up to clock. Paint red insulator over any "hot" parts in clock. The "power" cable will be about as dangerous as any current small appliance "leakage" since most have .045 mF caps from EACH power lead to chassis. UL specifies an allowable leakage level. 5 ma sounds familiar since that's the level that GFI's are supposed to trip at. There's a thought, wire it any way you want to, then plug it into a gfi ;-) hook all your clocks, smoke detectors, etc together and use just one gfi. the gfi will use more power than you're saving. have a good new year -larry / dallas |
#33
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A wall-wart alternative
Nick,
All the parts should be in the HOT side for safety. Move thre resistor from the bottom leg(neutral) to the top (hot) leg. Make the resistor bigger. Safer would be to use a small transformer to step the voltage down, then just put a diode in the secondary. That is what most large manufacturers who don't want to get sued do these days. Stretch |
#34
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#35
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Stretch wrote:
All the parts should be in the HOT side for safety. Move thre resistor from the bottom leg(neutral) to the top (hot) leg. The first old line cord I used was unpolarized... Make the resistor bigger. That eats into efficiency, and it might need to change with the required current. Right now, only the cap needs to change. Safer would be to use a small transformer to step the voltage down, then just put a diode in the secondary. Exactly what I want to avoid, with a thousand times the power consumption :-) Nick |
#36
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A wall-wart alternative
Nick wants to correct the power factor for the rest of
the house while he is at it...LOL wrote in message ... Stretch wrote: All the parts should be in the HOT side for safety. Move thre resistor from the bottom leg(neutral) to the top (hot) leg. The first old line cord I used was unpolarized... Make the resistor bigger. That eats into efficiency, and it might need to change with the required current. Right now, only the cap needs to change. Safer would be to use a small transformer to step the voltage down, then just put a diode in the secondary. Exactly what I want to avoid, with a thousand times the power consumption :-) Nick |
#37
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#38
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A wall-wart alternative
Nick just likes to reinvent the wheel, whilr ignoring all advances is
safety made along the way. When we are dealing with milliamps or microamps in the charging circuit, efficiency hardly seems an issue. Now on a battery only system, efficiency has an effect on battery life. He is using a non-rechargible battery that will be ruined by his recharging scheme. At these current levels, it won't blow up or catch fire, it just won't work when he needs it. It is a goofy thing to do for a once a yerar or twice a year battery change. Strange way to gain efficiency. Reinventing what has already been invented is rarely cost effective. You can buy something off the shelf that works for less than you can cobble together some kludge that will not work reliably. And for a smoke detector, reliability is EVERYTHING!!! Now he will have to respond to this. Probably will dig up something out of NREL :-) Stretch Stretch |
#40
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Stretch wrote:
Nick just likes to reinvent the wheel, whilr ignoring all advances is safety made along the way. How is describing an old CR psu reinventing anything? When we are dealing with milliamps or microamps in the charging circuit, efficiency hardly seems an issue. We know that isnt so. All those household appliances on standby drawing milliamps nedes a whole power generating station to supply. The CR supply uses less money and materials in construction too. In this case it also saves battery replacements - more material and energy waste - lives saved as a result of the battery still being available to work Now on a battery only system, efficiency has an effect on battery life. He is using a non-rechargible battery that will be ruined by his recharging scheme. At these current levels, it won't blow up or catch fire, it just won't work when he needs it. I wasnt aware that microamp charging would damage non rc cells. Is this true, can you offer a reference? It is a goofy thing to do for a once a yerar or twice a year battery change. whats goofy about saving lives? Strange way to gain efficiency. in what way is it strange? Reinventing what has already been invented is rarely cost effective. there is no reinvention here You can buy something off the shelf that works for less than you can cobble together some kludge that will not work reliably. not so. Go ahead and give us a link to one thats cheaper than this. And for a smoke detector, reliability is EVERYTHING!!! Yes, and my one complaint about Nicks application sits here. If either mains or battery fails, his detector wont sound. Imho if youre going to the trouble of running mains to the detector it makes more sense to pay the small extra and ensure it will sound if either mains or battery is alive. That issue can be solved simply by making the CR pass enough i to power the alarm during sounding. NT |
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Wall falling down? | UK diy | |||
Concrete retaining wall issue revisited. | Home Repair | |||
Retaining Wall in front of another Retaining Wall | Home Repair |