pier

Hello, I am new to computer programming. I would like to know the best way possible to start learning scripting. But I am confused with too many and different suggestions on the web. Could any of you with good experience with self learning share some info on this please ? I would also like to know if 'C' programming is a must know for me to start off with scripting. thanks, much in advance

Hello, How do you calculate the CFM requirement of a FAN to cool a Heat sink ? I am making a small cool box using peltier elements. Thanks

Hello, I work with some stand alone battery chargers for a project. I have some doubts on the discharge part of the Li-Ion battery. Generally we disconnect the battery from the load based on voltage sensing. My doubt is that Is there a concept called as current sensing also in the discharge mode ? For example: like a battery is only allowed to discharge for a defined time in this current and this could help in increasing the life time of the battery ? I just happened to hear this from somewhere and am not so sure if this is correct. I googled around a lot and still not arrived at a conclusion ??? ========================================================== In the charging mode we generally look at the current rather than the voltage to cut off charging process. ========================================================== If any of you came across this topic, Please share your experience. regards, Pier

Thanks AG for the reply. Any ways of measuring this gate charge ? Regards, Pier

Hello, While checking the N Channel Mosfet. I put the multimeter in the Beep mode (continuity mode) Probing the -ve probe at the Mosfet Drain (tab), the +ve probe at the Source pin - the multimeter reads 500+ ohms which is the body diode I think. Then Still probing the -Ve on the Drain I touch the +ve probe on the gate for a moment and then probe it back on the source it shows a dead short. I don't know why this happens. Any body knows about this, please share. The mosfet I used is FDD13AN0 from Fairchild initially I tried the same with the: BUK919 from NXP NTD5867NL and a couple more and all show the same. Regards Pier

I have a doubt regarding the charge-discharge cycle for Lithium-ion batteries. If the battery gets discharged to 50% and then charged to full, is it considered as one cycle? or if the battery gets discharged fully and gets charged again to full it is considered as one cycle ? Regards, Pier

Hello, I need an equal replacement for the part number 2SK533. This device is used in a Flow control board which is gone bad. I need to replace this with an alternative part and many vendors say that this part is no more manufactured. If any one knows about this part please contribute. I am not able to find a datasheet for this part. All that I got is attached. datasheet2.pdf

that was very useful, thanks

Hello, I am in search of some sheet which has the package details of smd resistors and capacitors. Some sheet which contains the package dimensions for a quick reference. Please share some resources you guys know about. Thanks Pier

hello, I am looking for the thread where AG had posted a corrected schematic of the RGB mood lamp which seems to be missing. Could anyone help posting the schemaic again (or may be AG could). Thanks much in advance Pier

Ok then I will increase the input voltage to about 18 or 19 volts. But I need to keep the battery at 13.55 as full charge condition, So I wanted to know wheather charging current automatically drops when voltage rises.

I have a doubt. If I charge a 12 volt battery with a constant current regulator (120mA) using lm317, The CC regulator is powered from a 15 volt 2 Amp power supply. The battery is a SMF 12v/1.2Ah type. will the current reduce if the voltage in the battery increases ? I have attached a diagram for clarity on the configuration.

I dont have a schematic because I bought it from an electronic store, The store owner told me that it could withstand Short ckt. I dont know how far its true. I think I would try the 100ohm power resistor.

Hello all, I have a constant current driver 350mA with an O/P voltage of 40 Vdc, I want to know a way to test the driver without the leds.

Hello, I am facing a problem in my circuit where I made it for switching of a light when the battery voltage reaches 10.55 volt. The battery is 12 volt 3.4Ah SMF type. The problem is: When the battery reaches 10.55 volt (roughly) the battery is disconnected from the load. When the battery is disconnected from the load the battery voltage rises a bit and turns on the relay again. This repeats and repeats. I don't know if the circuit I made is right. Could somebody help me to fix this ?

Does anybody have documents or links related to Best lab practices ? Some thing like how to use tools in the correct way or what to be used where and in which way. for Eg: When I used a skinned wire to connect it to a power supply, One of my senior told me that that was not the correct way to use and told me to use banana connectors instead. He also told me to follow standards in the LAB? Could someone help me with this? I searched and found it only for chemical and biology labs.

Me too live on the ground ;D. Water here reduces a lot in summer and Hydro stations are affected.

Due to summer season there is power cuts here . They call it load shedding. So need to prepare for it.

Hi AG :D :D :D ;D I dont live in a tree. I have a 13.5 volt 1.5A battery charger so that charges the battery and also lights up the leds. So when the power goes off it lights for some time taking back up from the battery. My previous image had some wrong calculations. In the image shown here i plan to have 4 such modules(led board 4nos and current regulator 4 numbers). So which would be the best power transistor to use ? the current of one module is 240mA.

when the mains is off and all leds are also off the voltage across the capacitor is 117 volts DC (reducing very very slowly) . The capacitors i used is 10uF/450volts, 3nos in parallel which makes 30uF.

Hello AG Do you mean the voltage across the led string when the mains voltage is disconnected and the led's are put off ?

So should i put a resistor across it to discharge it when it is put off ?

I fixed them with good ones, but the capacitors are still charged even after the led's are off . They give small shocks . I took the pcb in my hand after the led's were off, thinking they would be discharged .

While testing the board (old project with 52 led's) i applied just about +50 volts and found all the LED's start to work with a very dim light but around 4 of them were very very dim than the other 48 ones which were uniform in brightness. Is this because of the forward voltage rating or will those 4 of them fail fast ?

Hi AG Which manufacturer would be your next choice ?