Hi John,
Ok, SPST in series with 300b filament wire. Here is a link to a .MPG movie file: It's 1.5Mbytes
http://home.attbi.com/~laustin56/mov1.MPG
You can see when I turn the switch off the B+ climbs and then when I turn the switch back on the B+ stablizes back to normal.
So what do you think?
Ok, SPST in series with 300b filament wire. Here is a link to a .MPG movie file: It's 1.5Mbytes
http://home.attbi.com/~laustin56/mov1.MPG
You can see when I turn the switch off the B+ climbs and then when I turn the switch back on the B+ stablizes back to normal.
So what do you think?
Frank,
It's not the peak just past the posotive cycle I'm worried about at the moment, it's the fast + and - spikes.
These, I suspect are recovery spikes from the Schottky diodes in Pauls heater bridge.
I attempted to prove this by asking him to disconnect the bridge input. I expected the spikes to die immediately, but they go slowly. That is what I'd expect if he'd dissed the heater wire.
Any idea's?
Paul, it is the input to the bridge you're cutting?
Cheers,
It's not the peak just past the posotive cycle I'm worried about at the moment, it's the fast + and - spikes.
These, I suspect are recovery spikes from the Schottky diodes in Pauls heater bridge.
I attempted to prove this by asking him to disconnect the bridge input. I expected the spikes to die immediately, but they go slowly. That is what I'd expect if he'd dissed the heater wire.
Any idea's?
Paul, it is the input to the bridge you're cutting?
Cheers,
Hi Again,
Yes, we just missed each other on the internet super highway with our last posts.
Here is a movie (1.3Mb) with the switch wired in series with only one of the transformer leads going into the 300b rectifier circuit.
.http://home.attbi.com/~laustin56/mov1.MPG
I cycled the switch twice. The switch is "on" at the start of the movie.
I hope this is it. I am running out of solder moving that damn switch all over the place. ( Just Kidding )
Yes, we just missed each other on the internet super highway with our last posts.
Here is a movie (1.3Mb) with the switch wired in series with only one of the transformer leads going into the 300b rectifier circuit.
.http://home.attbi.com/~laustin56/mov1.MPG
I cycled the switch twice. The switch is "on" at the start of the movie.
I hope this is it. I am running out of solder moving that damn switch all over the place. ( Just Kidding )
Hi Paul,
It's not perfectly clear, but it looks as if the spikes go when thr switch is off.
If that is the case, then Frank's idea of bypassing each Schottky diode with a polyprop cap seems a good idea.
As for value, I'm not sure in high current circuits.
Frank, no doubt has a figure on the tip of his tongue.
Cheers,
It's not perfectly clear, but it looks as if the spikes go when thr switch is off.
If that is the case, then Frank's idea of bypassing each Schottky diode with a polyprop cap seems a good idea.
As for value, I'm not sure in high current circuits.
Frank, no doubt has a figure on the tip of his tongue.
Cheers,
I AM NOT CONVINCED.
Hi,
Handing me the hot potato?
From the mpeg files I watched in a loop I am not at all convinced that's where the problem stems from.
However it won't hurt to try a bit of noise killing...
Paul,
No need for polyprops,a simple polyester cap + resistor would do.
Make a network consisting of a 1K/1W and 0.100 mF/100V cap in series and wire it across each diode.
I notice other irregulaties on the sine waves though...no idea where those come from other then what I said before, polyprop caps let pass too much crap from the mains.
That's why I advise an ordinary electrolytic cap as the first filter cap anyway.
Cheers,
Hi,
Handing me the hot potato?
From the mpeg files I watched in a loop I am not at all convinced that's where the problem stems from.
However it won't hurt to try a bit of noise killing...
Paul,
No need for polyprops,a simple polyester cap + resistor would do.
Make a network consisting of a 1K/1W and 0.100 mF/100V cap in series and wire it across each diode.
I notice other irregulaties on the sine waves though...no idea where those come from other then what I said before, polyprop caps let pass too much crap from the mains.
That's why I advise an ordinary electrolytic cap as the first filter cap anyway.
Cheers,
I KNOW.
Hi John,
I know the filter is overkill to the extreme.
I'm just hoping to see a clear effect on the scope and take it from there.
An other reason is that Paul may have this value in his junkbox,10R is less likely.
Anyway,if this is where the spikes originate even a cap alone would show it on the scope IMO.
Cheers,
Hi John,
I know the filter is overkill to the extreme.
I'm just hoping to see a clear effect on the scope and take it from there.
An other reason is that Paul may have this value in his junkbox,10R is less likely.
Anyway,if this is where the spikes originate even a cap alone would show it on the scope IMO.
Cheers,
Hey CK,
I appreciate the thought.
The PWT was wound with a tap for 7.2v 1.5a for the 300b filament. The whole idea in the begining was to recitify to DC.
The amp sounds really good now, I'm just chasing the hum dragon.
How's your's sounding these days? Must have it broken in by now.
Do you have a next project?
I appreciate the thought.
The PWT was wound with a tap for 7.2v 1.5a for the 300b filament. The whole idea in the begining was to recitify to DC.
The amp sounds really good now, I'm just chasing the hum dragon.
How's your's sounding these days? Must have it broken in by now.
Do you have a next project?
Hey Paul,
That's cool. I went with AC heaters and was worried that I might have HUM problems. However, all seems to have turned out well. Just as I thought I couldn't get better sound... I swapped my 85db speakers for my Klipsch 98db speakers and ... and... I am now hearing things in music that I have never heard before.. I actually hear the fingers slide along the strings in some songs.
My next project will be a preamp. I am currently working out the details, but probably be transformer coupled. Will keep you informed..
ck
That's cool. I went with AC heaters and was worried that I might have HUM problems. However, all seems to have turned out well. Just as I thought I couldn't get better sound... I swapped my 85db speakers for my Klipsch 98db speakers and ... and... I am now hearing things in music that I have never heard before.. I actually hear the fingers slide along the strings in some songs.
My next project will be a preamp. I am currently working out the details, but probably be transformer coupled. Will keep you informed..
ck
SNUBBERS.
Hi Paul,
The snubber networks should be wired across each diode,so you'll need 4 of them.
As John pointed out the 1K is too high so we better either drop it and use the caps alone, or if you have four 10 Rs you can use those.
If I recall it correctly the middle tap and housing of the diode are the cathodes (negative) and the outer legs are the anodes.
Each network has to be mounted across cathode and anode of the diodes, // with it.
If my assumption is correct, the easiest way to go about it is to start for the center pin of the diodes and connect across to an used outer leg.
Cheers,
P.S. Ask John to check this as I will be offline this evening and tomorrow for most of the day.
Hi Paul,
The snubber networks should be wired across each diode,so you'll need 4 of them.
As John pointed out the 1K is too high so we better either drop it and use the caps alone, or if you have four 10 Rs you can use those.
If I recall it correctly the middle tap and housing of the diode are the cathodes (negative) and the outer legs are the anodes.
Each network has to be mounted across cathode and anode of the diodes, // with it.
If my assumption is correct, the easiest way to go about it is to start for the center pin of the diodes and connect across to an used outer leg.
Cheers,
P.S. Ask John to check this as I will be offline this evening and tomorrow for most of the day.
Hi,
Well I had to order some parts from digi-key to try the circuit snubbers.
Here is a list:
EF1104-ND .1UF/100VDC METAL POLY CAP
EF1124-ND .12/100VDC METAL POLY CAP
E1154-ND .15UF/100VDC METAL POLY CAP
E1184-ND .18UF/100VDC METAL POLY CAP
BC2091-ND CAP FILM MKP .1UF 160VDC 2%
OX100K-ND RES CERAMIC COMP 10 OHM 1W
OX82GK-ND RES CERAMIC COMP 8.2 OHM 1W
BC10W-2CT-ND RES 10 OHM METAL FILM 2W 5%
and that's it. Any suggestions or commnets?
Well I had to order some parts from digi-key to try the circuit snubbers.
Here is a list:
EF1104-ND .1UF/100VDC METAL POLY CAP
EF1124-ND .12/100VDC METAL POLY CAP
E1154-ND .15UF/100VDC METAL POLY CAP
E1184-ND .18UF/100VDC METAL POLY CAP
BC2091-ND CAP FILM MKP .1UF 160VDC 2%
OX100K-ND RES CERAMIC COMP 10 OHM 1W
OX82GK-ND RES CERAMIC COMP 8.2 OHM 1W
BC10W-2CT-ND RES 10 OHM METAL FILM 2W 5%
and that's it. Any suggestions or commnets?
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