class AB amp

[tikbalang]

ilang watts (or mW) ito?





.

[tony]

ilang watts (or mW) ito?

assuming an 8 ohm speaker load, with rails of 9volts, rms volts is about 3 volts, so a little over 1watt........
.

[j a y k e z]

nakita ko ang circuit na to sa youtube

[DJFEL]

abang neto..

[efren]

common topology used in AM/FM battery operated transistor radios...this might come handy, thanks for sharing +1

[brucetech]

ok to a...
 nice sharing..

[efren]

up, gusto paglaruan at gawin 12V para sa vehicle ko, ano-ano kaya ang maisugestyon para magamit sa 12V?

1. umpisahan ko na, gamit tayo TO-220 (TIP41/42) trannies sa output, para maikabet sa heat sink,
2. Resistor sa emmiter ng PNP at NPN power tranny, value=0.5R 2W?
3. Adjust bias res na 1K? add ng in4148?
4. Replace 470uF w/ 1000uF
waiting... yoohoo sir tony

[Roland]

common in old tv set.

[tony]

sa mga sinaunang transistor radios.... remember avegon?....

[Roland]

sa mga sinaunang transistor radios.... remember avegon?....

yong may litrato ni gabby conception at sharon cuneta?

buhay pa ba avegon nyo sir tony?

[efren]

i found this here http://redcircuits.com/Page33.htm

this satisfies my requirement for 12V operation, i'll play around with the bias, if anything goes wrong there's no costly damage, parts are a plenty at my junk bin

[tony]

yong may litrato ni gabby conception at sharon cuneta?

buhay pa ba avegon nyo sir tony?

nahingi ng kamag-anak...

[efren]

sa mga sinaunang transistor radios.... remember avegon?....

yes sir,  :




tuner board left, power amp board right

[ultrasonic™]

pamarka

naalala ko ang mga AM radio ko noon

[efren]

eto ang simpleng amp na ginagamit nung panahon ng mga germanium trannies at AM/phonograph players

a little retro




simplified

UPDATED CIRCUIT DESCRIPTION
The schematic for the updated amplifier is shown above.  Only the final two transistors are needed, since the input signal (from a CD player) is quite large and obviates the need for any preamp transistors.   A resistor voltage divider has been added at the input jack to convert stereo signals (non-existent in 1956) into mono for the single audio output.  Resistor values were hand-selected for this updated amp, and varied significantly depending on the individual transistors used.  An additional bias resistor (220 ohms) has been added at the base of the power transistor to limit output – otherwise the transistor tends to quickly overheat. Even with the added resistor, the heatsink of the 2N68 is warm to the touch.   The original 1956 amp used PNP transistors, and that is how the updated schematic has been drawn.  For the actual unit built in this project, NPN equivalent transistors were used, with appropriate reversing of the polarities (capacitors and battery).   A 2N35 transistor (NPN) was substituted for the CK722 (PNP) and a 2N95 (NPN) was substituted for the 2N68 (PNP).  These transistors are all dated from the mid 1950s and still work quite well.  Finally, an audio output jack has been added in parallel to the internal speaker.   This allows a modern user to connect earphones to the MiniAmp, and enjoy personal listening – tone quality is excellent.  For a modern germanium “surround sound” system, connect a pair of powered computer speakers to the MiniAmp output jack, and adjust volumes so that all three speakers are functioning.

Special thanks to Paul Penfield Jr. of Transistor Museum.