the tools to make EI's are a tool for spinning a bobin eg motor lathe and a counter and you can do this by hand as well keeping count.
so any one can do the EI's
the toridal needs 30k usd off tools, magazens and tape heads, gear heads.
there is no cheap option.
andy
sed me your email
i can send you some pics
so any one can do the EI's
the toridal needs 30k usd off tools, magazens and tape heads, gear heads.
there is no cheap option.
andy
sed me your email
i can send you some pics
I use big UI core, have you tried those, should work in a similar way like c-core, with seperate coils
Hi Andy,
As far as the light dimmer is concerned - a gross simplification. The on time had to be carefully balanced. By the time the M1.0 came out he had that licked. Before that time, the triacs would fire inconsistently at no low. This produced a "ticking" sound.
The last design used a regular EI transformer that created high rails of 125 VDC each. This was reduced by a high frequency switching "down converter" that simply varied the duty cycle. Very nicely done too!
-Chris
Yes, this was the staple power supply for most of their amps. What ever he did, those "transformers" would draw excessive current with a sine wave input. We got many ordered by technicians that we wouldn't take back (after warning them first). I ran the Canadian factory warranty service center and parts depot.
True, I was including the PM 2.0 which is a switcher, around 2 KHz I think it was.
As far as the light dimmer is concerned - a gross simplification. The on time had to be carefully balanced. By the time the M1.0 came out he had that licked. Before that time, the triacs would fire inconsistently at no low. This produced a "ticking" sound.
The last design used a regular EI transformer that created high rails of 125 VDC each. This was reduced by a high frequency switching "down converter" that simply varied the duty cycle. Very nicely done too!
-Chris
Hi Andy,
-Chris
Eva seems to be very well versed in these also. She certainly knows her stuff. This type of design makes far more sense at high power levels.
I can understand that for sure. Even the winding for EI types should use more than a drill and counter.
Now that is nifty! My interests and knowledge run more to analog circuits. You are way beyond my skill level here. I just sniff for that unmistakable burnt - sweet smell. You know the one.
Sure, bhomester at gmail dot com. Thank you.
I am afraid that you are probably correct there. Manufactures of consumer gear normally do not use the best parts available. I would normally turn to Hammond or <forgot the other one> as they are both located in Ontario where I live. I actually did get to meet Fred Hammond before he died. He was a super guy, very helpful.
-Chris
I am currently re doing my 3kw H class amp.
with smps would like to do down converter but time is to valuble to me.
have you worked on the crest amps?
andy
with smps would like to do down converter but time is to valuble to me.
have you worked on the crest amps?
andy
Hi Andy,
-Chris
Yes, but I sold my company about 10 years ago. So I haven't seen one for a long time now. I had more fun with lower powered good consumer amplifiers.
-Chris
Sorry for my intervention in this battle of Titans. In Greece there are 2 very serious workshops of transformer construction. The first be found in Thessalonika and made only EI transformers in verry high prices. The second be found in Athens and made only toroidal transformers in some lower prices. For toroidals i am a little reserved (because the solidity of their core depends on how much tight it is the winding of wires around the core and because the under layer of primary it is from thicker wire than the secondary then the strong tightening has some limit to not broken the primary wire) then i gave a special order as follows: 1) After the core formating and before the winding procces to dipped in enamel and left to dry. 2) During winding the wire dipped in enamel separatelly 3) Finally the whole construction fixed in a metal box with the use of epoxy resin. This extra work, it cost more 25euros per xformer. Finally when i deliver the xformer i left it in the shelf for 10 days to dry very well everything. Of course a such type xformer due to its metal case probably it has the most possible little electromagnetic radiation around it. Yet with so much care (i don't believe there is nothing furthermore of this) a verry little cracking of 50Hz heared from the core if you touch your ear on the case. Why this? Therefore it is worth the extra cost for a such type fortification of xformer?
I quote bellow a picture to view the construction
Fotios
I quote bellow a picture to view the construction
An externally hosted image should be here but it was not working when we last tested it.
Fotios
Hi Andy,
Hi Fotios,
I am afraid we are straying from the main topic though. Comments on build quality of transformers are weakly on topic though.
-Chris
Bowers and Wilkins yes, Aura no. Not unless the trade name is different here (eg. Crown and Amcron).
Hi Fotios,
No battle here. 😉 Also, you are not interrupting.
I am afraid we are straying from the main topic though. Comments on build quality of transformers are weakly on topic though.
-Chris
The classic soft-start power resistors in aluminium case bypassed by a relay can cause a lot of trouble when the relay fails to close. They don't go open until the temperature is enough to cook everything around them.
Also, in order to be reliable, the resistor and relay approach requires the amplifier circuit to be muted and put in standby mode (no bias) until the relay closes. Furthermore, the control circuit must ensure that the relay closes even in low line conditions.
An alternative approach is to place one or more low value power NTCs in series and bypass them with a relay. When placed in the primary side, this gets rid of both transformer flux imbalance inrush and capacitor bank inrush. I find this way more reliable, and it results in lower cost and a more compact layout.
In general, I find most people in this forum very reluctanct to any new ideas, circuits or working principles not matching the common practices of the past 30 years. The fact that a circuit hasn't been used for the past 30 years doesn't make it a bad circuit.
Also, in order to be reliable, the resistor and relay approach requires the amplifier circuit to be muted and put in standby mode (no bias) until the relay closes. Furthermore, the control circuit must ensure that the relay closes even in low line conditions.
An alternative approach is to place one or more low value power NTCs in series and bypass them with a relay. When placed in the primary side, this gets rid of both transformer flux imbalance inrush and capacitor bank inrush. I find this way more reliable, and it results in lower cost and a more compact layout.
In general, I find most people in this forum very reluctanct to any new ideas, circuits or working principles not matching the common practices of the past 30 years. The fact that a circuit hasn't been used for the past 30 years doesn't make it a bad circuit.
"I find most people in this forum very reluctanct to any new ideas, circuits or working principles not matching the common practices of the past 30 years. "
So, are you proposing anything new here? NTCs bypassed with relays have been around for more than 30 years.
So, are you proposing anything new here? NTCs bypassed with relays have been around for more than 30 years.
djk said:
Of course inrush suppresion NTCs have been available for a lot of time, and almost every SMPS uses them, but most audio amplifiers doesn't, either because there is no soft start or because they use a resistor.
Same happens with SMPS, they have been around for a lot of time and they have been routinely employed in almost every appliance requiring regulated DC voltages, except in audio amplifiers where we are still stuck at the iron age.
Hi,
I have absolutely no doubt that Thermistors whether a series string or one big version can adequately do the duty of soft start on a transformer (or SMPS).
I also have no qualms when various posters promulgate the use of either correctly sized Thermistors or resistors to achieve the current reduction required at start up.
However, the posters that conveniently forget the "problem" with Thermistors, namely second soft start requirement while the Thermistor is still warm, or worse hot.
Experienced builders will be aware of this, but for this to be of use to less experienced builders and newbies, I would ask that promoters of either version at least list the cons with the pros so that the readers can go and search out the (the deliberately omitted) information.
In my, not unique, situation my supply suffers irregular but fairly frequent power loss that can last just a few hundred mS to many seconds.
Thermistors are ineffective for current inrush here.
Even relay bypassed Thermistors are less effective than resistor if there are multiple shutdowns and restarts due to power loss.
Please be unbiased and promote your favourite fairly.
I have absolutely no doubt that Thermistors whether a series string or one big version can adequately do the duty of soft start on a transformer (or SMPS).
I also have no qualms when various posters promulgate the use of either correctly sized Thermistors or resistors to achieve the current reduction required at start up.
However, the posters that conveniently forget the "problem" with Thermistors, namely second soft start requirement while the Thermistor is still warm, or worse hot.
Experienced builders will be aware of this, but for this to be of use to less experienced builders and newbies, I would ask that promoters of either version at least list the cons with the pros so that the readers can go and search out the (the deliberately omitted) information.
In my, not unique, situation my supply suffers irregular but fairly frequent power loss that can last just a few hundred mS to many seconds.
Thermistors are ineffective for current inrush here.
Even relay bypassed Thermistors are less effective than resistor if there are multiple shutdowns and restarts due to power loss.
Please be unbiased and promote your favourite fairly.
McIntosh and BGW used NTCs and relays from the very start, 1971 on the MC2300 (small amplifiers did not have the relays).
The earliest BGW used a 5R/50W resistor and a relay with a fuse in series with the resistor in the event of relay failure, they went with NTCs in a very short period of time.
But in general you're correct in that most brands lacked this refinement (even though they need it).
The earliest BGW used a 5R/50W resistor and a relay with a fuse in series with the resistor in the event of relay failure, they went with NTCs in a very short period of time.
But in general you're correct in that most brands lacked this refinement (even though they need it).
the problem with the relay closed power resistor is i have seen lots of melted resistors,where the relay has failed for lots of reasons.
also there are issues with regulations relating to parts that you can connect to UK mains.
the ntc solves some off these points.
50 watt metal clads melt!
andy
also there are issues with regulations relating to parts that you can connect to UK mains.
the ntc solves some off these points.
50 watt metal clads melt!
andy
Hi,aandy said:
could you be helpful and point us to which regulation you are referring and where it can be consulted?
not upto date with the regs.
but they did state some where, that parts did have to be maked with aprovals for direct conection to the mains.
like the BS markings on instrument wire for mains conection.
this also applies to the mains leads and conectors like the power con.
british standards and dti will have a lot off the info.
but they did state some where, that parts did have to be maked with aprovals for direct conection to the mains.
like the BS markings on instrument wire for mains conection.
this also applies to the mains leads and conectors like the power con.
british standards and dti will have a lot off the info.
Hi,
you've covered mains cables, but what about the thermistor/s, resistor/s, relays/or not and delay timers that are the subject of this thread?
you've covered mains cables, but what about the thermistor/s, resistor/s, relays/or not and delay timers that are the subject of this thread?
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