Diode or Rectifier
- Thread starter gbrusseau
- Start date
From Wikipedia:
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which is in only one direction, a process known as rectification. Rectifiers have many uses including as components of power supplies and as detectors of radio signals. Rectifiers may be made of solid state diodes, vacuum tube diodes, mercury arc valves, and other components.
So, a rectifier is any one of a group of items that convert AC to DC, while a diode is one component that may be used in a rectifier. Diodes allow current to flow in only one direction, and as such, can convert AC to pulsating DC, but in order for complete rectification to occur, more than a single diode is required.
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which is in only one direction, a process known as rectification. Rectifiers have many uses including as components of power supplies and as detectors of radio signals. Rectifiers may be made of solid state diodes, vacuum tube diodes, mercury arc valves, and other components.
So, a rectifier is any one of a group of items that convert AC to DC, while a diode is one component that may be used in a rectifier. Diodes allow current to flow in only one direction, and as such, can convert AC to pulsating DC, but in order for complete rectification to occur, more than a single diode is required.
BillyGreen1973
Senior Member
the old mercury arc rectifiers are amazing to watch, mesmorising.
Have a look for them on you tube.
They used to be used to provide power for the high power lamps used in cinema projectors.
Have a look for them on you tube.
They used to be used to provide power for the high power lamps used in cinema projectors.
BillyGreen1973
Senior Member
also in simple terms, a silicon diode is the junction between N and P doped silicon. It is essentially two thirds of a transistor (NPN or PNP)
A diode is a
component
of a rectifier.
See, for example
http://www.kpsec.freeuk.com/powersup.htm#trs
e
The TV station I worked at long, long ago used a cage full of mercury vapor rectifiers to deliver 5800 volts DC at 10 amps to power the 50KW video transmitter. The rectifier cage was probably 8 feet on each side and 8 feet high. This was in the days when TV transmitters actually shut down at night (after the Late Movie). The mercury vapor rectifiers had a timer for the filaments that turned them on some 30 minutes before morning turn-on of the transmitter - it took that long for the big rectifiers (several feet tall) to reach operating temperature.
The tubes (valves) in the transmitter were ceramic and metal and the filament of each tube required 185 amps at 5 volts. The final amplifier had 5 of those tubes in parallel. Removing a tube required a puller that looked like an upside down car screw jack. There was a metal bar that went through the metal flanges of the tube and turning the handle of the "jack" pulled the tube from the socket. All the contacts were silver plated and the filament pins were about 1/2" (12mm) in diameter. The transmitter was on US channel 13 (~210MHz) so the "coax" to the antenna (on a tower 1100 feet tall)) was large copper piping (think 3" outer braid and 3/4" center conductor).
John
premelec
Senior Member
John... it's interesting how we're concerned about bitty amounts of mercury in compact florescents and such where we used to use mercury thyratrons and rectifiers with pools of the stuff not to mention diffusion pumps... I built a small [75 watt] transmitter 60 years ago using glass bulb mercury rectifiers which flashed with the Morse I was sending... cool man! And I cleverly figured out that I could wire two toggle switches so the first one turned on would heat the filaments and the next on the HV - and you didn't have to know which to throw first.
Glad you survived with 50KW TV station - I don't like being near that stuff! and rather like low power PICAXEs. Now for stories of vacuum tubes with kerosene heaters...
Glad you survived with 50KW TV station - I don't like being near that stuff! and rather like low power PICAXEs. Now for stories of vacuum tubes with kerosene heaters...
BillyGreen1973
Senior Member
A diode is strictly a 2 electrode (di =2, -ode =electrode) electronic device (initially thermionic),which may be even an LED. To rectify means to correct or put right. Aside from the latter term's modern AC to DC usage with semiconductor diodes, I understand a "Miss Rectifier" title amusingly applies in -ahem-certain circles!
Haha... yes, you're probably right
He was an electronics engineer in the RN and then the UKAEA.
But, by heck, when he was making things at home they'd be patiently made (and bodged) from all sorts of stuff he'd borrowed or had hoarded in old drawers.
He could have been a Kiwi , bless him
He was an electronics engineer in the RN and then the UKAEA.
But, by heck, when he was making things at home they'd be patiently made (and bodged) from all sorts of stuff he'd borrowed or had hoarded in old drawers.
He could have been a Kiwi , bless him
inglewoodpete
Senior Member
And at the other end of the technological scale was my first rectifier.
My first radio used a galena crystal and "catswhisker" to form the detector (rectifier) of a 'crystal set'. You had to fiddle around with the catswhisker wire to find just the right spot of the surface of the crystal to get the right effect - and radio reception.
I still have the crystal set packed away in a box somewhere.
I don't know what the kids of the future will do when AM broadcast radio is finally shut down.
My first radio used a galena crystal and "catswhisker" to form the detector (rectifier) of a 'crystal set'. You had to fiddle around with the catswhisker wire to find just the right spot of the surface of the crystal to get the right effect - and radio reception.
I still have the crystal set packed away in a box somewhere.
I don't know what the kids of the future will do when AM broadcast radio is finally shut down.
"I don't know what the kids of the future will do when AM broadcast radio is finally shut down."
Apart from a few brave hobbyists and experimenters and those in the middle of nowhere I doubt if the majority wiil even notice let alone give a damn.
But I reckon it'll be around for a while as the lowish/mediumish frequency stuff does have certain benefits.
Apart from a few brave hobbyists and experimenters and those in the middle of nowhere I doubt if the majority wiil even notice let alone give a damn.
But I reckon it'll be around for a while as the lowish/mediumish frequency stuff does have certain benefits.
Well, as we are reminiscing, I do remember staying in accommodation on a UK Post Office radio station site (a few years pre-BT), where at night the fluorescent lights in the accom block were either on or dim, never off. On gave them 240v, dim gave them pickup from the 100kW of short-wave from the aerial farm that surrounded us. Working on the wiring must have been fun. Probably it's still the same today.
As for a diode vs rectifier, well you can convert ac to dc with a more-than-two-terminal device (e.g. a triode, tetrode, pentode etc) but a diode is the minimum component that you can rectify with. There are lots of ways of making diodes but in the end they are just two-terminal gadgets that pass current one way. Some more fearsome than others.
As for a diode vs rectifier, well you can convert ac to dc with a more-than-two-terminal device (e.g. a triode, tetrode, pentode etc) but a diode is the minimum component that you can rectify with. There are lots of ways of making diodes but in the end they are just two-terminal gadgets that pass current one way. Some more fearsome than others.
premelec
Senior Member
AM & Corrosion
The simple AM radios we built with simple crystals and cat whisker could lead to a more useful information that corroded connections could rectify AM signals - I recall one detector made with a razor blade edge... this leads to the recognition that lots of oxidized materials can form rectifiers which can lead to harmonic generator spurious mixed signals etc... This may not be commonly taught but is learned by people using transmitters near nonlinear junctions. On this forum the issue of adequate bypassing is frequently brought up as something somewhat mysterious but necessary to do. Capacitors can and do act as inductors at various frequencies. Mostly CMOS has led us to be less cautious than the days of TTL spikes. We're living in a electromagnetic soup with all the RF devices around and shielding and non-oxidized contacts and such are part of the route to reliable operation of low power devices.
Connections bright and tight don't rectify - so - stay bright and tight!
The simple AM radios we built with simple crystals and cat whisker could lead to a more useful information that corroded connections could rectify AM signals - I recall one detector made with a razor blade edge... this leads to the recognition that lots of oxidized materials can form rectifiers which can lead to harmonic generator spurious mixed signals etc... This may not be commonly taught but is learned by people using transmitters near nonlinear junctions. On this forum the issue of adequate bypassing is frequently brought up as something somewhat mysterious but necessary to do. Capacitors can and do act as inductors at various frequencies. Mostly CMOS has led us to be less cautious than the days of TTL spikes. We're living in a electromagnetic soup with all the RF devices around and shielding and non-oxidized contacts and such are part of the route to reliable operation of low power devices.
Connections bright and tight don't rectify - so - stay bright and tight!
That's interesting about razor blades.
I'll have to see if I can pick up Five Live on my Gillette
(Actually I've just changed to King of Shaves. Half the price , blades last longer and I don't get ripped off by Gillette for the price of the blades).
I can't think of any component or device that escapes LCR totally.
A surpising example being the reactive overshoot of a PIC o/p when going into a high impedance load. Dig out a good 'scope and watch it.
Capacitors act as inductors at every frequency. Whether or not this has any impact on your circuit depends on the component value / characteristic and the application environment. And they have non-linear capacitance values wrt frequency , hence paralleled caps in many RF circuits for decoupling and filtering. You'll know this already , most won't.
Are we less cautious? Maybe in certain things , but certainly the proliferation of MOS junctions has made people more concerned about ESD protection etc.
Another superb PICAXE Forum digression. Long may it live
P.S. I'm more than happy to stay tight!
I'll have to see if I can pick up Five Live on my Gillette
(Actually I've just changed to King of Shaves. Half the price , blades last longer and I don't get ripped off by Gillette for the price of the blades).
I can't think of any component or device that escapes LCR totally.
A surpising example being the reactive overshoot of a PIC o/p when going into a high impedance load. Dig out a good 'scope and watch it.
Capacitors act as inductors at every frequency. Whether or not this has any impact on your circuit depends on the component value / characteristic and the application environment. And they have non-linear capacitance values wrt frequency , hence paralleled caps in many RF circuits for decoupling and filtering. You'll know this already , most won't.
Are we less cautious? Maybe in certain things , but certainly the proliferation of MOS junctions has made people more concerned about ESD protection etc.
Another superb PICAXE Forum digression. Long may it live
P.S. I'm more than happy to stay tight!
Great stuff. thanks all. So as I understand it, rectifiers are best at converting AC to half wave DC and diodes like the voltage already DC recified.
As for those vacuum tubes. I worked as a tech for a newspaper years ago and they had these tubes called Ignitrons that rectified and controled amps and voltage to the giant DC press motors. At normal operating speed the voltage to the motors was about 1600 volts at around 1200 amps. All controled by the Ignitrons. The mercury puddle would vaporize and you could see the tubes glowing purple and blue. First time I saw those tubes glowing, my first instinct was to run for my life. LOL
As for those vacuum tubes. I worked as a tech for a newspaper years ago and they had these tubes called Ignitrons that rectified and controled amps and voltage to the giant DC press motors. At normal operating speed the voltage to the motors was about 1600 volts at around 1200 amps. All controled by the Ignitrons. The mercury puddle would vaporize and you could see the tubes glowing purple and blue. First time I saw those tubes glowing, my first instinct was to run for my life. LOL
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Have a look at the animation near the bottom of the page here:
http://www.kpsec.freeuk.com/components/diode.htm
Four diodes making a rectifier.
e
http://www.kpsec.freeuk.com/components/diode.htm
Four diodes making a rectifier.
e
inglewoodpete
Senior Member
Well, Inglewoodpete... I've been rocking back & forth on the fence, but I must have it by now. I've always been suspicous of those fascist parts store vendors. Who do these store vendors think they are trying to distinguish a difference from a single component. Its nice to know that a rectifier is always silicon and a 0.7 volt drop across the junction and that diodes are masquerading as rectifiers. Or is it that silicon is masquerading as germanium. Next time I buy one, I'm going to ask the salesman for a rectifier diode. Its sort of like over here in the US, years ago thongs where those foot appliance they now call flip-flops. So dare I ask what a thong is now or is that for a new thread?
premelec
Senior Member
Rectitude...
Rectification is a function that can be done by a diode - or other methods like FETs and and fast relays and such. AC is 'rectified' to some sort of unipolar stuff [really lumpy for single phase and pretty smooth for 6 phase]. Full wave and half wave and so forth... Diodes in turn can be of various solid state materials or mercury pools with cathodes or vacuum tubes - the general characteristic is that they allow current to flow more freely in one direction than the reversed direction with various perfection or lack of it [e.g. see selenium rectifiers which we used before germanium and silicon - and smelled funny...].
I think there may have been a rock song "Come on baby rectifier... " sung by some poor engineer trying to get a power circuit working...
Rectification is a function that can be done by a diode - or other methods like FETs and and fast relays and such. AC is 'rectified' to some sort of unipolar stuff [really lumpy for single phase and pretty smooth for 6 phase]. Full wave and half wave and so forth... Diodes in turn can be of various solid state materials or mercury pools with cathodes or vacuum tubes - the general characteristic is that they allow current to flow more freely in one direction than the reversed direction with various perfection or lack of it [e.g. see selenium rectifiers which we used before germanium and silicon - and smelled funny...].
I think there may have been a rock song "Come on baby rectifier... " sung by some poor engineer trying to get a power circuit working...
BeanieBots
Moderator
Probably better off on a different forum!
You might get arrested for a wearing a thong on your feet in the UK
william47316
New Member
wrecked 'im? it bloody near killed 'imAs explained in the link in Post#2 I thought .... ?
"Rectifier" also has the advantage of easily being changed into a rude word which amused schoolboys of Stan's (and my Dad's) era.
Rectumfrier.
It's known as a fungal infection and you can get a cream for that :>
Just to add to the humor
donrecardo
Senior Member
I just read through all of this thread and didnt see anyone mention
selenium stick rectifiers . Lots of little square plates with a bolt through the middle . looking like a heatsink.
Surely I am not the only one old enough to remember those
Don
selenium stick rectifiers . Lots of little square plates with a bolt through the middle . looking like a heatsink.
Surely I am not the only one old enough to remember those
Don
william47316
New Member
i vaguely remember one of those in an ancient car battery charger. use longer selenium for voltage thicker selenium for current i read that somewhere. i think i was 8 or 10 at that time so i didnt know what it wasI just read through all of this thread and didnt see anyone mention
selenium stick rectifiers . Lots of little square plates with a bolt through the middle . looking like a heatsink.
Surely I am not the only one old enough to remember those
Don
And you had to cautious if replacing a selenium rectifier with a "new" silicon rectifier - the voltage under load coulod be appreciably higher (for tube type power supplies).
John
Right... I remember those Selenium plates bolted together. The ones that would smell bad like Premelec noted.
Hmmm, could it be that wearing thongs on your feet is whats causing that fungus condition?
After wearing them thongs for a while they would start to smell real bad too. Must have been made from selenium.
Hmmm, could it be that wearing thongs on your feet is whats causing that fungus condition?
After wearing them thongs for a while they would start to smell real bad too. Must have been made from selenium.