strange blue laser optics

Started by John Larkin in sci.electronics.design2 years ago 42 replies

I got a couple of these, to maybe cure UV-set...

I got a couple of these, to maybe cure UV-set epoxy. https://www.ebay.com/itm/High-Power-Purple-405nm-Pointer-Burning-Light-Beam-Pen-with-Battery-Cha rger-USA/383162483108?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 It came with a big lithium battery and a charger. Two weird things: If I shoot it at a white wall, I can see the spot with my right eye, but not with my


AC charger for NiCd AA battery?

Started by Borrall Wonnell in sci.electronics.design9 years ago 8 replies

Hi all, I have a device which is powered by a solitary 1.2V 800 mA NiCd cell. An AC wall charger (5VAC @ 180 mA) is used to charge the cell. ...

Hi all, I have a device which is powered by a solitary 1.2V 800 mA NiCd cell. An AC wall charger (5VAC @ 180 mA) is used to charge the cell. This is done via a simple half-wave rectifier that is built in to a small circuit board inside the device. The battery sees about 90 mA (true RMS). It seems strange to use a hard-to-find AC power source rather than a commonly available DC wall ada...


lLi-Ion battery charging question

Started by billbowden in sci.electronics.design4 years ago 31 replies

Just purchased from E-Bay a couple 8.4 volt (900maH) li-ion rechargeable batteries in the little 9 volt package. It came with a charger that...

Just purchased from E-Bay a couple 8.4 volt (900maH) li-ion rechargeable batteries in the little 9 volt package. It came with a charger that accepts 2 batteries to be charged at the same time. The (+) terminals of the charger are shorted together, and the (-) terminals are also shorted together. I'm wondering if it is safe to connect two Li-Ion batteries in parallel if the state of charg...


Constant Voltage Transformer Operation?

Started by amdx in sci.electronics.design9 years ago 7 replies

I recently repaired a marine battery charger. It was set up to charge 3 separate 12v batteries. The repair was simple the charger had a...

I recently repaired a marine battery charger. It was set up to charge 3 separate 12v batteries. The repair was simple the charger had a *shorted 40uf 660v ac capacitor. The capacitor is connected across a winding on the transformer. This is the usual constant voltage transformer configuration. This is the extent of what I think I know. Can someone describe the operation of a constant vo...


USB to TP4056 charger - why is the diode there?

Started by Peabody in sci.electronics.design2 years ago 4 replies

This is the relevant part of the schematic of an 18650 battery charger and boost converter (to 5V)...

This is the relevant part of the schematic of an 18650 battery charger and boost converter (to 5V) module: https://i.postimg.cc/Tw7X35Fq/USB-to-TP4056.jpg And here's the module: https://www.aliexpress.com/item/32870411748.html Coming from the USB power pin, there's a series Schottky diode and a very low value resistor. The resistor is found in the TP4056 datasheet typical applic...


Why charger failed

Started by AK in sci.electronics.design2 years ago 5 replies

This phone charger failed and I would like to diagnose why it failed. It was running quite warm before it...

This phone charger failed and I would like to diagnose why it failed. It was running quite warm before it failed. https://www.dropbox.com/s/7d9hztgdfp9znr3/CellPhoneCharger1.JPG?dl=0 https://www.dropbox.com/s/0cmemsca888ttv2/CellPhoneCharger2.JPG?dl=0 https://www.dropbox.com/s/lhomejqgem4wffw/CellPhoneCharger3.JPG?dl=0 The one pic looks like some component melted and spread that yel...


12V Circuit breakers for auto battery chargers

Started by Anonymous in sci.electronics.design9 years ago 13 replies

I have a battery charger that is rated at 2, 15, or 100 amps. It's a Everstart WM-1510 ma model. (Walmart). I found that Schumacher has...

I have a battery charger that is rated at 2, 15, or 100 amps. It's a Everstart WM-1510 ma model. (Walmart). I found that Schumacher has an identical charger model SE-1510 ma. That says these Everstart chargers are made by Schumacher. Anyhow, the 12v circuit breaker has died and will not reset. That seems to be the most common problem on all chargers. My question is this. The Schu...


Can a charger for sealed lead acid cell be used for wet lead acid cell ?

Started by Daku in sci.electronics.design10 years ago 4 replies

I am not very familiar with battery technology, and hence my query. A few years ago I designed and built a simple sealed lead acid cell charger....

I am not very familiar with battery technology, and hence my query. A few years ago I designed and built a simple sealed lead acid cell charger. It also had a battery status indicator, and worked fine. It has been sitting in the drawer since then. I was wondering if the same can be used for wet lead acid cells, and if not what modifications are needed ? Thanks in advance for your hints and s...


Design Battery Charger using H-bridge Mosfet concept

Started by samson.bunty1986 in sci.electronics.design9 years ago 10 replies

Hi, Am planing to design a battery charger using H bridge mosfet configuration . Battery spec as follows: Battery voltage ---24V Battery...

Hi, Am planing to design a battery charger using H bridge mosfet configuration . Battery spec as follows: Battery voltage ---24V Battery capacity -- 45Ah So the charging current should be 10% of battery capacity. am i correct?? So the charging current is 5A. Am having some querys. What are the mosfets hve to be used?? Is it 2 N-channel & 2 P channel mosfets?? How to controll th...


The ebay 10$ solar powered flashlight FM radio and mobile phone charger

Started by Jan Panteltje in sci.electronics.design8 years ago 9 replies

I wrote: > The ebay 10$ solar powered flashlight FM radio and mobile phone charger > ebay item 370856410707 >...

I wrote: > The ebay 10$ solar powered flashlight FM radio and mobile phone charger > ebay item 370856410707 > http://www.ebay.com/itm/370856410707?ru=http%3A%2F%2Fwww.ebay.com%2Fsch%2Fi.html%3F_sacat%3D0%26 _from%3DR40%26_nkw%3D370856410707%26_rdc%3D1 > > http://panteltje.com/pub/solar_FM_radio_flashlight_speaker_side_IMG_4229.JPG > nice screws.. > > No headphone jack, but a real very loud


The ebay 10$ solar powered flashlight FM radio and mobile phone charger

Started by Jan Panteltje in sci.electronics.design8 years ago 5 replies

The ebay 10$ solar powered flashlight FM radio and mobile phone charger ebay item 370856410707 ...

The ebay 10$ solar powered flashlight FM radio and mobile phone charger ebay item 370856410707 http://www.ebay.com/itm/370856410707?ru=http%3A%2F%2Fwww.ebay.com%2Fsch%2Fi.html%3F_sacat%3D0%2 6_from%3DR40%26_nkw%3D370856410707%26_rdc%3D1 This is my second option to put the Geiger counter in. the thing arrived late this night, curiosity opened it: http://panteltje.com/pub/solar_FM_radio_flas


Battery System Design

Started by OldGuy in sci.electronics.design7 years ago 7 replies

Subsystem consists of: 115 VAC Car Battery Charger 12 V Car Battery 12 VDC to Laptop Power Converter Laptop Charger provides full...

Subsystem consists of: 115 VAC Car Battery Charger 12 V Car Battery 12 VDC to Laptop Power Converter Laptop Charger provides full time current to charge the Car Battery and to power the laptop power converter to laptop. When AC goes off, car battery provides power until depleted. The laptop is to run all the time until battery depleted. Laptop max 90 Watts. 115 VAC Car...


Logic problem

Started by Anonymous in sci.electronics.design4 years ago 16 replies

I have two 12 volt batteries that need to be charged in parallel and then switched in series for 24 volts and the charger disconnected. Need to...

I have two 12 volt batteries that need to be charged in parallel and then switched in series for 24 volts and the charger disconnected. Need to do this with a single double pole, double throw relay. Any ideas?


Charging time for Ultrafire 18650 6800 mAh battery

Started by Andy in sci.electronics.design3 years ago 44 replies

I would like to find out how long to charge the above battery. Charger puts out 500 mAh. Thanks.

I would like to find out how long to charge the above battery. Charger puts out 500 mAh. Thanks.


Sizing a battery charger

Started by G. Morgan in sci.electronics.design9 years ago 35 replies

What is a good formula for the needed minimum current (and over voltage) for charging batteries? Use a 12V car battery for example, how...

What is a good formula for the needed minimum current (and over voltage) for charging batteries? Use a 12V car battery for example, how much 'trickle charge' is needed to keep them alive when not being used? Thanks.


Battery Charger Protecttion

Started by Anonymous in sci.electronics.design8 years ago 7 replies

Hi, I am using the following chip from linear technologies http://cds.linear.com/docs/en/datasheet/4062fb.pdf How can I stop common...

Hi, I am using the following chip from linear technologies http://cds.linear.com/docs/en/datasheet/4062fb.pdf How can I stop common user to connect input (Vcc, pin 10) to voltages greater than 10 Volts? Jessica


Charging time for 12 V battery

Started by Anonymous in sci.electronics.design9 years ago 18 replies

I have a 12 Volt battery, 9.5 Ah that uses a 12 volt charger 1.0 amp. Assuming the battery is completely discharged, is there a way to...

I have a 12 Volt battery, 9.5 Ah that uses a 12 volt charger 1.0 amp. Assuming the battery is completely discharged, is there a way to determine how long to charge ? Thanks, Andy


Photoflash capacitor charger idea

Started by bitrex in sci.electronics.design6 years ago 4 replies

https://www.dropbox.com/s/yxnnefxugivhhe8/Photo%20Jan%2008%2C%2011 %2044%2052%20AM.jpg?dl=0 Charge big cap to dump thru strobe lamp --...

https://www.dropbox.com/s/yxnnefxugivhhe8/Photo%20Jan%2008%2C%2011 %2044%2052%20AM.jpg?dl=0 Charge big cap to dump thru strobe lamp -- ----Android NewsGroup Reader---- http://usenet.sinaapp.com/


Audio transformer impedance

Started by bitrex in sci.electronics.design6 years ago 11 replies

I'm using one of these little PCB mount impedance matching transformers "backwards" in my junk box cap charger, and am trying to select a...

I'm using one of these little PCB mount impedance matching transformers "backwards" in my junk box cap charger, and am trying to select a value of DC blocking capacitor to put in front of it. I think I've been trying to use a value of a few nanofarads in the prototype and it's not right, there is a lot of ringing and nastyness coming out of the secondary. Here is the datasheet on th...


controllers; program in C

Started by Anonymous in sci.electronics.design7 years ago 32 replies

Hello. I want to build, for fun, a battery charger and I want to use this as an excuse to experiment with a controller chip that you can...

Hello. I want to build, for fun, a battery charger and I want to use this as an excuse to experiment with a controller chip that you can program in C. Are PIC devices the way to go? I noticed they have a free C compiler available for some of the chips. As always, $$$ is a factor. I see several projects for battery chargers on line, posted by experimenters. I'm still asking here thou. I w...