markw Posted March 19, 2003 Share Posted March 19, 2003 Also what is a rectifier and what does it do? I don't think I have one on this Stromberg-Carlson integrated amp and I wonder if I could add one and would it help? Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted March 19, 2003 Share Posted March 19, 2003 Mark, It's a device that converts AC (sine wave) to DC (flat line). These can be tubes like the 5AR4 or EZ81 or it can be a solid state device. The SS deal is essentially a diode, but there's a couple different types. Additionally, after the current is rectified there's often a residual ripple that can cause hum. This is where capacitors came in, they pass AC but block DC. In various parts of the amp circuit there can be AC, DC or both on the wire. Usually caps are used to filter out the DC, leaving only the AC which is the actual music signal. Caps also store energy, big ones near the power supply are often doing this in addition to filtering out the residual AC ripple. Of course, there's a Ph.D.'s worth of detail left out here, but you gotta start somewhere.... Your amp will have one, but if there's not a separate tube it's probably a small SS bridge rectifier under the chassis near the PS. Tom Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 19, 2003 Share Posted March 19, 2003 Mark, If your amp doesn't have one there will be no gain or possibilty for you to add one. A rectifier has to have taps from the main PS to power it and if a PS doesn't have the taps then no point in going further. Besides your amp would have no where to use the current that would be rectified without a big redesign. Did you ever find a schematic for the amp ?? If so send me a copy and I'll look it over for key parts to replace. Craig Quote Link to comment Share on other sites More sharing options...
AnalOg Posted March 19, 2003 Share Posted March 19, 2003 Mark, I'm a bit confused with your explaination. If the rectifier turns ac to dc, then how does ac get back into the circuit, and if your using dc in the circuit why would caps have to block it? Tom Quote Link to comment Share on other sites More sharing options...
lynnm Posted March 19, 2003 Share Posted March 19, 2003 Trust me that integrated of yours does have a rectifier in its power supply. Short of running the amp on batteries it cannot work without a rectifier. Quote Link to comment Share on other sites More sharing options...
dougdrake Posted March 19, 2003 Share Posted March 19, 2003 I think you can get a rectifier if you eat too many jalapeno peppers. Quote Link to comment Share on other sites More sharing options...
lynnm Posted March 19, 2003 Share Posted March 19, 2003 AAH Yesssssss ! Jalapeno Sauce inspired Johnny Cash to write " Ring of Fire " Quote Link to comment Share on other sites More sharing options...
JohnA Posted March 19, 2003 Share Posted March 19, 2003 Doug to the rescue!!!! Quote Link to comment Share on other sites More sharing options...
dougdrake Posted March 19, 2003 Share Posted March 19, 2003 ---------------- On 3/19/2003 12:49:55 PM John Albright wrote: Doug to the rescue!!!! ---------------- I usually leave that sort of work to fini, but he hasn't been as prolific lately. Must be busy driving relatives to the airport! DD Quote Link to comment Share on other sites More sharing options...
sunnysal Posted March 19, 2003 Share Posted March 19, 2003 doug I must correct you....that's rectafryer, totally unrelated to the audio rectifier. those of us who have suffered from this debiliting syndrome would appreciate keeping your terminology straight. tony Quote Link to comment Share on other sites More sharing options...
dougdrake Posted March 19, 2003 Share Posted March 19, 2003 ---------------- On 3/19/2003 1:55:28 PM sunnysal wrote: doug I must correct you....that's rectafryer, totally unrelated to the audio rectifier. those of us who have suffered from this debiliting syndrome would appreciate keeping your terminology straight. tony ---------------- Of course you are correct, Tony. My bad. Is the rectafryer a "George Foreman" product? Quote Link to comment Share on other sites More sharing options...
Deang Posted March 20, 2003 Share Posted March 20, 2003 For your reading pleasure: "A stereo contains a power supply that converts 110-volt alternating current into lower-voltage direct current. This direct current is ultimately what powers the speakers. The stereo's power supply first lowers the voltage with the help of a transformer. Alternating current from the power line flows back and forth through a coil of wire in this transformer, the primary coil, and causes that coil to become magnetic. Since the coil's magnetism reverses 120 times a second (60 full cycles of reversal each second), along with the alternating current, it produces an electric field--changing magnetic fields always produce electric fields. This electric field pushes current through a second coil of wire in the transformer, the secondary coil, and transfers power to that current. There are fewer turns of wire in the secondary coil than in the primary coil, so charges flowing in the secondary coil never reach the full 120 volts of the primary coil. Instead, more current flows in the secondary coil than in the primary coil, but that secondary current involves less energy per charge--less voltage. In this manner, power is transferred from a modest current of high voltage charges in the primary coil to a large current of low voltage charges in the secondary coil." "Having used the transformer to produce lower voltage alternating current, the power supply than converts this alternating current into direct current with the help of four diodes and some capacitors. Diodes are one-way devices for electric current and, with four of them, it's possible to arrange it so that the alternating current leaving the transformer always flows in the same direction through the circuit beyond the diodes. The diodes act as switches, always directing the current in the same direction around the rest of the circuit. The capacitors are added to this circuit to store separated electric charge for the times while the alternating current is reversing and the diodes receive no current from the transformer. The capacitors store separated charge while there is plenty of it coming from the transformer and provide current while the alternating current is reversing. Overall, the stereo's power supply is a steady source of direct current." From -- http://howthingswork.virginia.edu/audio_amplifiers.htmlhttp://howthingswork.virginia.edu/audio_amplifiers.html' target=_blank> Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 20, 2003 Share Posted March 20, 2003 Dean, You definitly read to much !! Quote Link to comment Share on other sites More sharing options...
jt1stcav Posted March 20, 2003 Share Posted March 20, 2003 The residence pipe organ my dad built for our house back in '83 has a rectifier (big gray box/red plaque in top center of jpg)...if I'm not mistaken, it coverts 120 house current into 220 to power the musical instrument. If you fiddle with its innards, it should then be called a "rectumfryer!" (it'll fry yer a$$ fer sure!) Quote Link to comment Share on other sites More sharing options...
WMcD Posted March 20, 2003 Share Posted March 20, 2003 In the organ project, if there is a device which converts 120 a.c. to 240 a.c., or any a.c. to a.c. converter, it is a transformer. The general term for what is being asked about is a diode. The word actually indicates it has two connection points. As mentioned, it switches on when forward biased with voltage, and therefore it conducts current. When it is reverse biased, it doesn't turn on. Tom Edison placed a plate in a vacuum filled lightbulb and connected a wire lead out of the glass envelope. He found that it was possible to get electrons to flow from the filament to the plate when the plate was positive, relative to the filament. That was a pretty good trick in that two pieces of wire (or plates and filaments) separated by a vacuum should not conduct any current. It became called The Edison Effect. He never did much with it. Another early diode was the gallium (sp?) "crystal" used in crystal radios. It was a solid state device. It is used as a detector. In short, the radio signal is a sine wave where the amplitude is modulated in accord to the music. "AM" radio. It averages out to zero, so is diffiult to detect. However, as in a power supply, if you can use a diode to turn the a.c. to d.c. Just think of the a.c. to d.c. converter in a hi-fi. If your a.c. line voltage moved from 120 volts to 240 volts and back (call that a carrier modulated with music) the d.c. output would increase and decrease, giving you the music. Lee DeForest discovered that if you put a screen (or grid) in between the filament and the plate something even odder happened. The flow of current from the flament to the plate (per Tom E.) would be controlled by the voltage applied to the screen. It was a valve. Small voltage changes on the screen controlled large amounts of current. It acted as an amplier. He called it an Auditron. Because there were three leads, it was also called a triode. But now you had an interesting situation. The crystal radio device was a type of germanium diode. The tube diode did the same sort of thing. The triode tube acted as a valve. Question: can you make a triode valve out of a germanium crystal? or anything similar. Yup, eventually the transistor was developed. It uses three leads. So it is a solid state triode substitute for the triode tube. It acts like a valve too. (More than you asked about.) Looking at the rectifier/diode device in history. The first ones were the germanium crystal (very little power capacity) and the tube diode (still used in some tube amps). Then there was the selenium rectifier. Better current carrying capacity. They look like sandwiched square plates and were used in later tube type amps to subsititute for tube rectifiers. Now there are silicon diodes used as rectifiers. They look like little black peas with two leads. Sometimes they are heat sinked. Gil Quote Link to comment Share on other sites More sharing options...
mike stehr Posted March 20, 2003 Share Posted March 20, 2003 Audion. Quote Link to comment Share on other sites More sharing options...
markw Posted March 21, 2003 Author Share Posted March 21, 2003 Craig, I emailed you a schematic, (it was scanned from the inside of the bottom cover.) Thanks Quote Link to comment Share on other sites More sharing options...
jt1stcav Posted March 21, 2003 Share Posted March 21, 2003 Thanks Gil for the education lesson (that's how we learn around here). And that device is called a rectifier; I obviously had the wrong description for it. You stated: "Then there was the selenium rectifier. Better current carrying capacity. They look like sandwiched square plates and were used in later tube type amps to subsititute for tube rectifiers." They look like a tiny heat sink of sorts. One of my 50's vintage Zenith vacuum tube AM/FM radios had a bad selenium rectifier...the radio was playing when it failed; it produced a terrible smell when it overloaded and caught on fire. Because it's always LIVE when plugged into a wall outlet (even when the radio was off), I immediately unpluged the radio! My dad later repaired/restored the classic Zenith bakelite radio, and replaced the burnt rectifier with a new silicon diode. It has a wonderful tone and I listen to the news/weather with it every morning in the kitchen. Quote Link to comment Share on other sites More sharing options...
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