Hi Tea Bag,
saying "chill out" does not stop Trans destroying his project.
Trans is aware there are dangers.
Telling him how to do it safely would be a far better response.
saying "chill out" does not stop Trans destroying his project.
Trans is aware there are dangers.
Telling him how to do it safely would be a far better response.
Tea-Bag said:
T-Bag, good info on the unloaded voltage of the tranny, thanks.
I don't know if most of us connect the ground (earth) leg when testing circuits prior to installing them in the enclosure. What would you connect it to, if not the enclosure?
GFCIs are designed to trip their internal breakers when they sense returning voltage on the ground leg instead of the neutral leg. It may keep you from being shocked, but it won't protect the circuit if its wired incorrectly. Maybe a subtle point, or simply different wording.
Sorry if I am nit-picking.
Ron
Renron said:
I think being specific when talking electricity and shock hazard is a good thing!
I am certainly not an authority in DIY. But have built a few things and had lots of FUN.
But for a transformer test, I guess no earth connected for me.
Other than that, before a chassis, I do tie a Green Gator clip lead to an IEC ground connector to the heatsink for sure.
I find that using my cheap Variac that Papa recommended, has saved plenty of mis-haps. The thing shakes a little when I have things crossed.....Never used the lightbulb trick, since the variac seems to avoid most issues.
I dont think members should be offended when a topic repeats itself...There is a lot of info (and other things) on the F5 thread, some not clear to an absolute beginner.
I think we all need to have thick skin, because communication of these matters globally is difficult, and open to confusion.
It's worth a level of frustration. The F5 is a damn fine amp.
Tea-Bag said:
Very well stated, I wholehearted agree!Also being a neophyte to electronics, not residential electrical, I'm easily confused by where and how to connect various devices.
Perfect example the Thermistor; should be connected prior to the transformer and in series, not //. I had to look it up on Google.
What is common knowledge for some, is black magic to others. We watch in awe some of the conversations here, and if we are lucky we get a SMALL fragment of understanding. It takes me a long time to "get it".
The patience and help ARE appreciated. I give back to our community when I can, and in so doing repay the kindness and knowledge others have showed me, which leads to more people enjoying the art of DiyAudio.
Ron
PS ?
Here is a question for Peter Daniel, though anyone can answer:
What happens to the sound when less capacitance is used for filtration in the PS? I recall you using 10-15k uf per side in your Zv9 build.
Thank you,
Chris
Here is a question for Peter Daniel, though anyone can answer:
What happens to the sound when less capacitance is used for filtration in the PS? I recall you using 10-15k uf per side in your Zv9 build.
Thank you,
Chris
Re: PS ?
If there is too little capacitance then 100Hz from the bridge rectifier will end up on the audio signal when the volume is turned up.
chrismercurio said:
If there is too little capacitance then 100Hz from the bridge rectifier will end up on the audio signal when the volume is turned up.
The lower you go in power supply capicitance the greater the power supply ripple you will have. Eg instead of 24 +/- 0.2V you might have 24 +/- 0.5V.
This may or may not be a big problem. It will depend on the PSRR of the amp. If it is a problem then you will hear hum coming through your speakers. There are other issues that are negative in nature which I am sure others will talk about (I am lazy).
My recommendation is, use as much capacitance as you can afford.
If you have a budget to follow then here is a list of items That
you should not skimp on.
1. Heatsinks
2. Transformer VA rating
3. Capacitors for power supply
If you still have plenty of spare change left over after that, then consider using higher quality components in the amp design (better quality resistors etc)
This may or may not be a big problem. It will depend on the PSRR of the amp. If it is a problem then you will hear hum coming through your speakers. There are other issues that are negative in nature which I am sure others will talk about (I am lazy).
My recommendation is, use as much capacitance as you can afford.
If you have a budget to follow then here is a list of items That
you should not skimp on.
1. Heatsinks
2. Transformer VA rating
3. Capacitors for power supply
If you still have plenty of spare change left over after that, then consider using higher quality components in the amp design (better quality resistors etc)
If you want some really great power supply boards and really good caps at a great price check out BrianGT's miniAleph power supply boards. They are large, tough, thick copper, beautiful gold on black with room for 6 caps each. Michael Percy Audio has Nichicon KG Gold Tune power supply caps for sale. 10kuF 35V for about $4-$5. Cheap. Boards are $9 each. Not bad at all.
Uriah
Uriah
Good to know. I think I have 200,000uF of Nichicon KG Gold Tune in 50V laying around, but $4-5 each is WAY less than what I paid years ago.
no they don't.Renron said:
The usual RCCB GFCI run the two phase leads, flow (Live) and return (Neutral) through a current transformer.
The output of the current transformer detects the DIFFERENCE between the flow and return currents.
The trip activates when this difference exceeds the set limit. (in the UK we generally have 10mA 30mA and 100mA RCCBs for domestic use).
It's not just mains frequency ripple components that exist on the supply rails.
The signal frequency is also seen as a ripple on the supply rails.
At higher audio frequencies one can observe the saw tooth profile of the mains re-charging the supply voltage followed by the ramp of discharge and superimposed on this is the music wave form.
As the caps get smaller the charge and discharge ramps get steeper, but at the same repetition frequency and the music waveform becomes more prominent.
The tops of these waveforms (maximum supply voltage) are about the same as the quiescent voltage on the PSU when zero audio signal is on the output of the amplifier.
The minimum of the ripple will be at it's maximum during quiescent conditions. At this time the ripple will be small due to the low current demand of the amplifier. The AMP PSRR will determine how much of this quiescent ripple gets through to the speaker. This comes out as very low level hum for the 50/60Hz and 100/120Hz components. But the AMP PSRR is often at it's best at these low frequencies so the hum is suppressed very well.
The higher frequency components come out the speaker as buzz and noise (white). The very high frequencies will be attenuated less than the lower frequencies due to falling slope of the AMP PSRR as frequency rises.
As the output current to the amplifier rises the ripple on the supply lines increases.
The only thing that "hides" the increased PSU supply noise is the noise of the music. But the music cannot hide all of it. We hear some of the increased PSU noise components mixed in with the very varying music signal.
In the limit, as the output approaches maximum power of the amplifier, the troughs in the PSU ripple come down to the level that the output signal clips due to asking for too much output voltage relative to the supply voltage.
Small smoothing capacitors make this series of audio artefacts worse than when using large smoothing capacitance.
It can be ameliorated by drawing very low currents from the PSU.
i.e. play at quiet reproduction levels or use high efficiency speakers.
Peter Daniel goes the latter route. 96dB speakers on ~+-1500uF smoothing and gets sound quality that satisfies his desires and targets.
If one uses low efficiency speakers and/or demands high SPLs then small smoothing capacitors will deteriorate the sound quality that comes from the speakers.
The signal frequency is also seen as a ripple on the supply rails.
At higher audio frequencies one can observe the saw tooth profile of the mains re-charging the supply voltage followed by the ramp of discharge and superimposed on this is the music wave form.
As the caps get smaller the charge and discharge ramps get steeper, but at the same repetition frequency and the music waveform becomes more prominent.
The tops of these waveforms (maximum supply voltage) are about the same as the quiescent voltage on the PSU when zero audio signal is on the output of the amplifier.
The minimum of the ripple will be at it's maximum during quiescent conditions. At this time the ripple will be small due to the low current demand of the amplifier. The AMP PSRR will determine how much of this quiescent ripple gets through to the speaker. This comes out as very low level hum for the 50/60Hz and 100/120Hz components. But the AMP PSRR is often at it's best at these low frequencies so the hum is suppressed very well.
The higher frequency components come out the speaker as buzz and noise (white). The very high frequencies will be attenuated less than the lower frequencies due to falling slope of the AMP PSRR as frequency rises.
As the output current to the amplifier rises the ripple on the supply lines increases.
The only thing that "hides" the increased PSU supply noise is the noise of the music. But the music cannot hide all of it. We hear some of the increased PSU noise components mixed in with the very varying music signal.
In the limit, as the output approaches maximum power of the amplifier, the troughs in the PSU ripple come down to the level that the output signal clips due to asking for too much output voltage relative to the supply voltage.
Small smoothing capacitors make this series of audio artefacts worse than when using large smoothing capacitance.
It can be ameliorated by drawing very low currents from the PSU.
i.e. play at quiet reproduction levels or use high efficiency speakers.
Peter Daniel goes the latter route. 96dB speakers on ~+-1500uF smoothing and gets sound quality that satisfies his desires and targets.
If one uses low efficiency speakers and/or demands high SPLs then small smoothing capacitors will deteriorate the sound quality that comes from the speakers.
all of that explanation is in the Forum.nicoch46 said:
But some folk refuse to do the research.
Be informed before you make decisions.
It applies to all your lifestyle decisions.
If I cared to, I could check just how much of that I have learned since I joined the Forum. It would not be a little!
AndrewT said:
AndrewT,
Thanks for catching that, my mind and fingers were on two separate thought tracks at the time............
Don't know how I got that confused. I know better! Thanks,
Ron
I took too long, and the edit time ran out on my above post, so here it is;
I wrote, "GFCIs are designed to trip their internal breakers when they sense returning voltage on the ground leg instead of the neutral leg"
I should have been exact and left out the word "leg" in the above ground reference. My bad.
Ripped straight from EC&M . Com (Electrical Construction and Maintenance)
"If a ground fault exists with some of the current flowing to ground and not returning on the neutral through the transformer, then the sum of the current flowing on the hot and neutral will not be zero and differential current will be detected. The GFCI's electronic circuitry then measures its magnitude. If it reaches a predetermined level (the GFCI trip threshold) for a given duration, a signal causes the trip coil to energize and the circuit to open. Written by Jack Wells, Vice President of Corporate Development for Pass & Seymour/Legrand.
UL requires the GFCI's to trip at 6mA, although it may take several seconds at this amperage level.
Ron
I wrote, "GFCIs are designed to trip their internal breakers when they sense returning voltage on the ground leg instead of the neutral leg"
I should have been exact and left out the word "leg" in the above ground reference. My bad.
Ripped straight from EC&M . Com (Electrical Construction and Maintenance)
"If a ground fault exists with some of the current flowing to ground and not returning on the neutral through the transformer, then the sum of the current flowing on the hot and neutral will not be zero and differential current will be detected. The GFCI's electronic circuitry then measures its magnitude. If it reaches a predetermined level (the GFCI trip threshold) for a given duration, a signal causes the trip coil to energize and the circuit to open. Written by Jack Wells, Vice President of Corporate Development for Pass & Seymour/Legrand.
UL requires the GFCI's to trip at 6mA, although it may take several seconds at this amperage level.
Ron
your quote from the ECM states it correctly.Renron said:
What you posted as your interpretation of the EC&M is wrong, with or without the word leg.
is this your interpretation of what UL states?Renron said:
This seems wrong as well.
Andrew is right.
This device detects only a difference between neutral and live currents.
The current lost can go directly to ground if the device to protect is grounded
or through your body if the device to protect is not grounded.
This permits to protect persons in contact with the live wire: the current
through their body cannot exceed a determinated value.
This device detects only a difference between neutral and live currents.
The current lost can go directly to ground if the device to protect is grounded
or through your body if the device to protect is not grounded.
This permits to protect persons in contact with the live wire: the current
through their body cannot exceed a determinated value.
AndrewT,
Your knowledge of electronics far exceeds mine, but I can read.
Quote from same article written by Jack Wells, the VP of Pass & Seymore/Legrand. Perhaps he is wrong too.
"A GFCIs. It's important you note that the "let-go" threshold is between 6mA and 18mA. The trip level of 6mA required for personnel-protection GFCIs by UL is based on this let-go current threshold."
"When installing and testing GFCIs, you should know that they do not trip instantaneously. In fact, while they typically trip in 25 ms or so at fault currents exceeding 20 to 30mA, they are permitted by UL to take several seconds to trip at fault currents in the 6mA range."
If you would care to read the entire article in whole, you can find it here:
EC&M article on GFCI
Man, you are one tough cookie!
In practice, if the current is flowing through the ground (wire or earth) then there is a "differential current", and the breaker is tripped. It is sensed by the differential between the hot and neutral, I agreed with you on that earlier. But if a differential exists it has to be going somewhere------ground wire or earth ground, like I said "instead of the neutral leg".
Your knowledge of electronics far exceeds mine, but I can read.
Quote from same article written by Jack Wells, the VP of Pass & Seymore/Legrand. Perhaps he is wrong too.
"A GFCIs. It's important you note that the "let-go" threshold is between 6mA and 18mA. The trip level of 6mA required for personnel-protection GFCIs by UL is based on this let-go current threshold."
"When installing and testing GFCIs, you should know that they do not trip instantaneously. In fact, while they typically trip in 25 ms or so at fault currents exceeding 20 to 30mA, they are permitted by UL to take several seconds to trip at fault currents in the 6mA range."
If you would care to read the entire article in whole, you can find it here:
EC&M article on GFCI
Man, you are one tough cookie!
In practice, if the current is flowing through the ground (wire or earth) then there is a "differential current", and the breaker is tripped. It is sensed by the differential between the hot and neutral, I agreed with you on that earlier. But if a differential exists it has to be going somewhere------ground wire or earth ground, like I said "instead of the neutral leg".
this long reply confirms that you acknowledge that your posted interpretations of what was printed were wrong.Renron said:
The printed versions are right, it's the way you are reading them and drawing conclusions that is suspect.
I see how my statement was misinterpreted, by my choice of wording was poor. I apologize.
The GFCI does not sense the earth/ground, but the differential current between the hot and neutral when that differential current is flowing through the ground wire or earth ground instead of the neutral.
OK?
UL requires the GFCI's to trip at 6mA, although it may take several seconds at this amperage level.
is this your interpretation of what UL states?
This seems wrong as well.
Comments?
The GFCI does not sense the earth/ground, but the differential current between the hot and neutral when that differential current is flowing through the ground wire or earth ground instead of the neutral.
OK?
UL requires the GFCI's to trip at 6mA, although it may take several seconds at this amperage level.
is this your interpretation of what UL states?
This seems wrong as well.
Comments?