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#1
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Silicon rectifiers ?
Don't want to get into the valve/silicon, which is best, debate. You makes
yer choices and that's OK by me. It's all down to the schematic and what you believe in.... I use silicon. Don't need a heater and low voltage drop...... IN4007 ? .. keep seeing it on schematics .... what's wrong with BY127 ? ....seems to have a better spec.. or .. I now use encapsulated industrial bridges.... About 1" square. Bolt down solid to the chassis with a 1/4" nut and bolt, have four Lucar/spade connectors.... cost about £2 and are rated at 1500 PIV at 35 AMPS !!! They don't get very warm with 500mA through them , so a heat sink is not an issue !! Any comments ? Kind regards jim |
#2
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"Yves Monmagnon" wrote in message ... "jim" wrote in message ... Don't want to get into the valve/silicon, which is best, debate. You makes yer choices and that's OK by me. It's all down to the schematic and what you believe in.... I use silicon. Don't need a heater and low voltage drop...... IN4007 ? .. Me too ! Just shunt each diode with about 1000 to 2000 pF (2000V) ceramic cap. Some use a "snubber" (around 0.01 to 0.1 µF in serie with 100 to 500 Ohms) accross the HV winding, not tested. I was annoyed with spikes noise in a phono preamp before I do that. UF 4007 seems OK w/o caps. keep seeing it on schematics .... what's wrong with BY127 ? ....seems to have a better spec.. or .. I now use encapsulated industrial bridges.... About 1" square. Bolt down solid to the chassis with a 1/4" nut and bolt, have four Lucar/spade connectors.... cost about £2 and are rated at 1500 PIV at 35 AMPS !!! They don't get very warm with 500mA through them , so a heat sink is not an issue !! Any comments ? Kind regards jim Eh, salut , Yves.... L'Ardeche.... eh... mon dieu ! Now using 4 pin industrial silicon bridges. No caps across them. 10H 500mA 50 ohm LC choke smoothing with 0.22uF 1500v polypropylene snubber caps either side of the choke joined together and taken down to earth followed by 2 x 470uF 450v caps in series with 220k balancing resistors across them.... This does everything I need best wishes mon ami jim |
#3
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Yves Monmagnon wrote: "jim" wrote in message ... Don't want to get into the valve/silicon, which is best, debate. You makes yer choices and that's OK by me. It's all down to the schematic and what you believe in.... I use silicon. Don't need a heater and low voltage drop...... IN4007 ? .. Me too ! Just shunt each diode with about 1000 to 2000 pF (2000V) ceramic cap. Some use a "snubber" (around 0.01 to 0.1 µF in serie with 100 to 500 Ohms) accross the HV winding, not tested. I was annoyed with spikes noise in a phono preamp before I do that. UF 4007 seems OK w/o caps. I quite often use a pair 6 amp single diodes in a voltage doubler circuit to make +500v, with plenty of 470 Uf caps and a big choke. There is a tendency for the noise at the output of an amp connected to such a supply to have pulse spikes at 100 Hz intervals. These are greatly reduced by placing a 0.1 uF across the HT secondary winding. The pulses often come from the switching in the circuit causing the resonances in the power tranny to be excited like a tank circuit on a transmitter, and the result is that the energy finds its way around earth wires. Bu placing the 0.1 uF across a HT winding, the F of the resonance is lowered, so it doesn't seem to transfer so easily around by stray inductance or capacitances. This simple method also stops the switching transients from being propagated down the mains wiring to other equipments. I have found the caps across the diodes do very little. But then I try to have my diodes sitting well away from the audio circuit, and have the whole PS in an enclosed box, at least on preamps, so the RF noise doesn't seem to get into the audio path. Sometimes its hard to see why there are these low level pulses in the output of an amp. Sometimes they get in from test gear connected, and sometimes they appear with one amp, and not another, and usually, its an earthing loop problem. With the input to a power amp left open, there should only be the noise generated by the resistor baising V1, and no 100 Hz pulses. I like SS rectifiers, and its good to see some silicon working its guts out on behalf of their masters, the tubes. I got used to high current rectification, and how to prevent its noise from spreading when I built a few SS amps, one of which has 2 x 100,000 uF caps for each +/- 70v rail for a stereo 2 x 300 watt amp. I used a steel box to encase the PT, and diodes, and I was careful with earth path wiring. I got N&D less than 0.005% at 299 watts. There are no caps or snubber networks across the diodes. If there is a problem with the earth paths, even with snubbers/caps/etc, one could still get noise introduced. The 35 amp bridges are quite nice to use. Patrick Turner. keep seeing it on schematics .... what's wrong with BY127 ? ....seems to have a better spec.. or .. I now use encapsulated industrial bridges.... About 1" square. Bolt down solid to the chassis with a 1/4" nut and bolt, have four Lucar/spade connectors.... cost about £2 and are rated at 1500 PIV at 35 AMPS !!! They don't get very warm with 500mA through them , so a heat sink is not an issue !! Any comments ? Kind regards jim |
#4
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HI Jim
Where can you buy the Bridges? Thanks Phil jim wrote: Don't want to get into the valve/silicon, which is best, debate. You makes yer choices and that's OK by me. It's all down to the schematic and what you believe in.... I use silicon. Don't need a heater and low voltage drop...... IN4007 ? .. keep seeing it on schematics .... what's wrong with BY127 ? ....seems to have a better spec.. or .. I now use encapsulated industrial bridges.... About 1" square. Bolt down solid to the chassis with a 1/4" nut and bolt, have four Lucar/spade connectors.... cost about £2 and are rated at 1500 PIV at 35 AMPS !!! Where can you buy the Bridges? Thanks Phil They don't get very warm with 500mA through them , so a heat sink is not an issue !! Any comments ? Kind regards jim |
#5
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"Philip Lawrence" wrote in message ... HI Jim Where can you buy the Bridges? Thanks Phil jim wrote: Don't want to get into the valve/silicon, which is best, debate. You makes yer choices and that's OK by me. It's all down to the schematic and what you believe in.... I use silicon. Don't need a heater and low voltage drop...... IN4007 ? ... keep seeing it on schematics .... what's wrong with BY127 ? ....seems to have a better spec.. or .. I now use encapsulated industrial bridges.... About 1" square. Bolt down solid to the chassis with a 1/4" nut and bolt, have four Lucar/spade connectors.... cost about £2 and are rated at 1500 PIV at 35 AMPS !!! Where can you buy the Bridges? Thanks Phil They don't get very warm with 500mA through them , so a heat sink is not an issue !! Any comments ? Kind regards jim Hi, Philip, Depends where you are in the world, I suppose. The ones I use are made by either General Rectifier or International Semiconductor bought from RS Components in Corby, Northamptonshire. They have a huge range of encapsulated bridges from 1A to 35A with solder or dry connections. and PIVs up to 1600V I like the single bolt fixing ones 'cause they're simple to mount and the spade connections avoid any danger of heat damage when wiring them up RS are at http://rswww.com kind regards jim |
#6
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"jim" wrote in message ...
Don't want to get into the valve/silicon, which is best, debate. You makes yer choices and that's OK by me. It's all down to the schematic and what you believe in.... I use silicon. Don't need a heater and low voltage drop...... IN4007 ? .. keep seeing it on schematics .... what's wrong with BY127 ? ....seems to have a better spec.. or .. I now use encapsulated industrial bridges.... About 1" square. Bolt down solid to the chassis with a 1/4" nut and bolt, have four Lucar/spade connectors.... cost about £2 and are rated at 1500 PIV at 35 AMPS !!! They don't get very warm with 500mA through them , so a heat sink is not an issue !! Any comments ? Kind regards jim go for the gusto and get some silicon carbide high voltage schottky diodes. no switching noise in the first place! jm2c ken |
#7
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(Ken Gilbert) wrote
go for the gusto and get some silicon carbide high voltage schottky diodes. no switching noise in the first place! Are they available to mortals yet? Got a link? cheers, Ian |
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