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# gamelektro

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3. ## DS1621 pc thermometer !!!! about the voltage limit in SCL and SDA input?????

i made the project DS1621 pc thermometer http://www.electronics-lab.com/projects/pc/010/index.html There is something i want to ask? 1. about voltage limiters (R1, DZ2, R2, DZ1) on the SCL clock input and SDA data input. how to look for the value for resistor and dioda zener for that project, i mean 4700 ohm and 5 volt dioda zener, what formula used in searching the value for that resistor and dioda zener. ? how to count it ? until we get the value for resistor and dioda zener?. 2.i'm learning the source code, but there is something i don't understand. temperature = (temperature_int * 256 + temperature_frac) / 128 * 5 / 10 If temperature_int >= 128 Then temperature = temperature - 256 i don't understand about the code, does anyone can help me to explain this code and explain the formula code? Please help. i'm sorry about the english sentence i'm doing my best to write it. Thank You
4. ## Voltage Limiter in DS1621 pc thermometer

i made the project DS1621 pc thermometer http://www.electronics-lab.com/projects/pc/010/index.html There is something i want to ask? 1. about voltage limiters (R1, DZ2, R2, DZ1) on the SCL clock input and SDA data input. how to look for the value for resistor and dioda zener for that project, i mean 4700 ohm and 5 volt dioda zener, what formula used in searching the value for that resistor and dioda zener. ? how to count it ? until we get the value for resistor and dioda zener?. 2.i'm learning the source code, but there is something i don't understand. temperature = (temperature_int * 256 + temperature_frac) / 128 * 5 / 10 If temperature_int >= 128 Then temperature = temperature - 256 i don't understand about the code, does anyone can help me to explain this code and explain the formula code? Please help. i'm sorry about the english sentence i'm doing my best to write it. Thank You
5. ## Need Help Voltage Regulator 12 vDC using 7812

Hello Mr, what type trafo must i used? Trafo With the CT ( Center Tap ) or Without CT.? The trafo 12v/1,5Amp not sold In my country, there only have 12v/1Amp. I Have a trafo 12v/1 amp without a CT ( I buy it this morning) and 12v/300mA with CT ( already have it ). So Mr which must i choose for the trafo to make the voltage regulator with output 12 Vdc, ? Mr, it is possible to make the Voltage Regulator 12vdc without 7812?, just using the trafo,dioda and capasitor.? Can we do that?!!!! and if we can do that please tell me about the picture schematic? sorry if my english not very well?? Thank You
6. ## Need Help Voltage Regulator 12 vDC using 7812

C1 = 2000uF C2 = ..?.. C3 = ..?.. D1 -D4 = what type diode must i use? 1N4001 or 1N4004 Please Tell me the value for C2 and C3 from the picture
7. ## Need Help Voltage Regulator 12 vDC using 7812

I need Voltage regulator from ac to dc 12 v but using 7812 please tell me the schematic circuit? or where i can download the schematic
8. ## DS1621 pc thermometer

http://www.electronics-lab.com/projects/pc/010/index.html I can't find the lm 2936-z5 .can 78L05 powered the 2 IC ds1621 without external volt ???