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1  Electronics Forums / Projects Q/A / Re: 1-25 volt power supply on: April 19, 2014, 09:07:29 PM
It is almost the same as the other circuit.
Why does it have two opamps? One opamp has a gain of about 200,000 which is plenty of gain for it to be the error amplifier. One opamp will need to be a non-inverting amplifier.

Also, the simple circuit has nothing to limit the output current.
2  Electronics Forums / Electronic Projects Design/Ideas / Re: extending an CFL electronic ballast on: April 17, 2014, 06:20:09 PM
ALL household compact fluorescent light bulb circuits I have seen show 4-pins glass bulbs. They have a filament at each end to heat the gas and reduce the starting voltage.

Sams talks about a 2-pins glass bulb with a starter that shorts it then opens when it heats. The ballast makes 500V to 600V when the starter opens to start the light.
3  Electronics Forums / Electronic Projects Design/Ideas / Re: 2 pin compact fluorescent lamp to 4 pin socket? on: April 17, 2014, 05:17:26 PM
you mean to say i should've gotten these ??:
http://www.ebay.com/itm/321293131731  (36W)

about $~28 total (price + shipping) -- hardly inexpensive. i wasn't just buying any CFL (which are around $~7 or so), these are UV lamps.
Are you trying to kill bugs with UV?
The 36W glass light looks like two 2-pins lights side-by-side. No filaments.
4  Electronics Forums / Electronic Projects Design/Ideas / Re: 2 pin compact fluorescent lamp to 4 pin socket? on: April 17, 2014, 08:39:30 AM
I have some modern CFL light bulbs that have burned out. Their glass coil has 4-wires, not 2-wires and there is a filament at each end the same as those huge old glass fluorescent tubes.

I saw 2-wire CFL glass lamps about 18 years ago because my daughter had one for her desk light.
5  Electronics Forums / Electronic Projects Design/Ideas / Re: extending an CFL electronic ballast on: April 17, 2014, 08:33:04 AM
The photo on the ballast shows two CFL bulbs with 4-wires each. But your OLD CFL bulbs have only 2-wires each.

The ballast starts the bulb by heating its filament at each end. Your OLD bulbs do not have filaments, they are started with an OLD starter thingy that creates a high voltage spike.

DO NOT overload a ballast with too many bulbs because then it will get hot and burn out or catch on fire.

Why not buy modern inexpensive CFL light bulbs that have a small electronic ballast attached to the base?
6  Related to Electronics / Components trade / Re: analog electronics on: April 16, 2014, 07:47:21 PM
Your English is horrible.
Why not ask in your own language on a website in your country?
7  Electronics Forums / Electronic Projects Design/Ideas / Re: 2 pin compact fluorescent lamp to 4 pin socket? on: April 15, 2014, 11:36:29 AM
A 4-pins compact fluorescent lamp tube has a filament at each end for starting.

A 2-pins compact fluorescent lamp is probably VERY OLD and used a huge and heavy inductor as a ballast to provide a high voltage spike to start.

It is too bad that you bought old junk from e-bay.
8  Electronics Forums / Electronics chit chat / Re: Circuit analysis on: April 15, 2014, 11:24:49 AM
R2 and the signal's source impedance form a voltage divider. C2 and the signal's source impedance form a lowpass filter.

R3 and R4 form another voltage divider that loads down the first voltage divider.

C3 and R3 form a highpass filter.

R3 and C4 form another lowpass filter.

The signal's source impedance in series with R3 calculated with R1 set the DC and very low frequency voltage gain of the opamp.

C1 and R1 form another lowpass filter.

 

9  Electronics Forums / Electronics chit chat / Re: doubt in active device on: April 14, 2014, 07:38:44 AM
A diode DOES NOT produce energy. Instead a battery or a generator produce electrical energy.
A diode is a rectifier. Why do you not understand?
10  Electronics Forums / Microelectronics / Re: about 555 circuit on: April 14, 2014, 07:35:39 AM
I answered this question in the forum on the other website.
Look at the datasheet for the LM555 that tells you all about it.
11  Electronics Forums / Electronics chit chat / Re: voltage across capacitor on: April 14, 2014, 07:33:37 AM
R2 and the 12V battery charge C. The voltage across C will be almost 12V when C is almost fully charged.
12  Electronics Forums / Electronics chit chat / Re: doubt in active device on: April 13, 2014, 05:54:22 PM
A diode does not produce power. A battery or a generator produce power.
A diode is a rectifier to convert AC into DC.
13  Electronics Forums / Projects Q/A / Re: 0-30V Stabilized Power Supply on: April 11, 2014, 05:04:09 PM
R21 simply allows C8 to slow down the switching of U3.
Instead increase the value of R17 so that the LED does not turn on when there is a small output load.
14  Electronics Forums / Projects Q/A / Re: 0-30 Vdc Stabilized Power Supply on: April 10, 2014, 02:59:12 PM
Here is a version modified for 36v ac
You forgot to calculate that the single 2N3055 output transistor and the tiny 2N2219 driver transistor will melt if the output current is 3A and the output voltage is low or is shorted.

36VAC produces a peak of 50.9V which causes the positive unregulated supply to be 48.9V. Then the output transistor heats with 47.5V x 3A= 142.5W. 60W is very hot fore it so it will be destroyed with 142.5W.
You can work out the heating of the tiny 2N2219 driver transistor yourself.

That is why our fixed and improved version uses a 28VAC or 30VAC transformer, two 2N3055 output transistors and a BD139 modern power transistor as their driver.
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