I suppose that with a quantity purchase from Caddock or Mills that it can't be a mix of different values? I ask since there are probably many out there building a high power version of the X, similar to the Aleph 2. In that case we will be looking for something other than 0.22ohms. Probably something like 0.47 as in the original Aleph 2 or 0.68 if built based on the great ideas from Ian MacMillan. Any ideas?
Andrew
Andrew
ungie.
with 0.47ohms you enter the realm of the metal film, for me that would be panasonic digikey-type stuff.
coulomb
the 915 in free air is derated at 1.25 W, the 916,925,930 are 2.25W in free air.
Peter,
right, the audio grade resistor, I looked at:
http://www.millsresistor.com/audio.htm
there is something wrong with the power rating probably a spelling error, I 'll give those guys a call tomorrow.
The mra-5 is as long as the mrp-3, 0.563 inch
Either Percy has a stock that is 5 years old or that is another mistake on the mills site.
Anyways, I think is time to either make up our minds or move on.
As far as I am concerned it's down to either Mills mrp-3 or Mills mra-5. I will find out what's the difference tomorrow and let you guys know.
with 0.47ohms you enter the realm of the metal film, for me that would be panasonic digikey-type stuff.
coulomb
the 915 in free air is derated at 1.25 W, the 916,925,930 are 2.25W in free air.
Peter,
right, the audio grade resistor, I looked at:
http://www.millsresistor.com/audio.htm
there is something wrong with the power rating probably a spelling error, I 'll give those guys a call tomorrow.
The mra-5 is as long as the mrp-3, 0.563 inch
Either Percy has a stock that is 5 years old or that is another mistake on the mills site.
Anyways, I think is time to either make up our minds or move on.
As far as I am concerned it's down to either Mills mrp-3 or Mills mra-5. I will find out what's the difference tomorrow and let you guys know.
Attention all, I talked to Jeff Mills himself:
MRA-5 (audio grade) vs. MRP5 (precision grade)
1) the audio type has alumina substrate (Al2O3 for the initiated) which as better heat properties than steatite in MRP3, that explains why the same form factor, 0.563 x 0.17 inch diameter is rated at 5W vs 3W in the MRP3.
2) the audio type has tinned OFC lead and the MRP has tinned Cu clad steel leads
3) this is not a difference per se since we were going to get non inductive design anyways, the MRA has standard Aryton-perry windings.
MORE GOOD NEWS!!!!
The MRA-5 IS CHEAPER!!!
The quoted price is
USD 0.96/each for 500
UDS 0.86 /each for 1000
BOTTOM LINE LET'S GET THE MRA-5!
The lead time is 3-4 weeks and I MUST COMMIT TO AN EXACT NUMBER NOW, MILLS wants a CC number at the time of ordering which will be charged at th time of shipping.
AS a result all interested parties should email me immediately with quantity and information this window of opportunity will be open until next
Tuesday, Feb 4th 2003 at NOON EST.
The date is FINAL, there won't be ANY EXTENSION WHATSOEVER.
The number of pieces I have on tuesday will determine the price braket we are in.
I will email you back immediately after the deadline with info about where to send payment. As soon as the I have the payment in my hands the order will go out.
Please use my zipcode 02148 (USA) to figure out shipping. I will use regular mail or UPS, your choice. If you want fast delivery calculate the extra amount.
The payment should be in the form of MO, cashier check, personal check (good one only please), international money order WHATEVER FORM payment IN USD that can be deposited directly in a US BANK.
I am thinking about PAYPAL but I haven't made up my mind yet so for right now is NO PAYPAL. Anyway, one person sending a check with mail will slow down the whole group so there is no overall gain.
I expect the payment from the US or CANADA to be here in about a week after I send you the notice. I will be a little more tolerant with international orders. It depends how much exposure I will have, if it's a couple of hundred $ is no big deal the order will go out, if I am waiting for $1000 it's a different matter.
MEMO:
I received 5 emails which is not too bad. However, two had NO shipping info. I set the deadline in four days so we can get the resistors sometimes soon, before next X-mas!
We must meet a minimum of 500 before the deadline, too, so please make up your mind quickly... and don't forget your address!
thank you
Kevin,
the main difference is that the Mills are non inductive and lower tolerance 1%.
While the first aspect could be viewed as a subjective matter, the most unequivocal benefit here is to have a low resistance spread (2%) with the Mills as opposed to a 10% spread possible with the Vishay. That could account for quite large differences in the source resistor drop even if your mosfet are perfectly matched. I am sure there are 1% WW resistors out there that are chaper than the Mills but as a whole I think the Mills are quite attractive for the price.
the main difference is that the Mills are non inductive and lower tolerance 1%.
While the first aspect could be viewed as a subjective matter, the most unequivocal benefit here is to have a low resistance spread (2%) with the Mills as opposed to a 10% spread possible with the Vishay. That could account for quite large differences in the source resistor drop even if your mosfet are perfectly matched. I am sure there are 1% WW resistors out there that are chaper than the Mills but as a whole I think the Mills are quite attractive for the price.
Normal Wirewound resistors - how much inductance do they have?
I came across the following measurements, which seem beliveable (lots of others that didn't):
- at 6 kHz the reactance is equal to the resistance (ie 0.22ohm)
- at 6 kHz the reactance is 0.75 ohm
Haven't done an analysis of the effect of this in circuit, but it must surely be significant.
Nic
I came across the following measurements, which seem beliveable (lots of others that didn't):
- 12kohm, 10 watt wirewound - 600 millihenries,
- 60 ohm, 10 watt wirewound - 2.1 millihenries
- 17.5 ohm, 15 watt wirewound - 530 microhenries,
- 0.39 ohm, 5 watt wirewound - 10 microhenries
- at 6 kHz the reactance is equal to the resistance (ie 0.22ohm)
- at 6 kHz the reactance is 0.75 ohm
Haven't done an analysis of the effect of this in circuit, but it must surely be significant.
Nic
MEMO:
For those of you that just tuned in this is a remender that in two days applications for this purchase will be closed and the order will be finalized.
As of right now the first milestone has been reached, the total order is 560, that includes yours truly.
The WIKI contains about 720 pieces, so if within two days I don't hear from the missing users, I'll just assume that they changed their minds.Coincident with the order closure an email will go out to the privileged few. This email will contain the correct price and payment instructions.
Please remember that you request has to include your complete shipping information in order to be valid.
Thank you!
This will be the LAST MEMO I am sending out.
We are getting dangerously close to the deadline that is in 24 hrs. At this point we have all the people we were supposed to get on board. We certainly would like to have more!
Let me remind you further that if you did not send me your address your personal email WILL NOT be considered as a VALID request.
A couple of people have not done so, yet.
The reason I am so adamant on this address business is multifaceted.
From the convenience standpoint your address gets put in a database from which shipping labels are printed ALL AT ONCE.
From the standpoint of my financial protection sending your address gives me a certain confidence that you mean serious business. I know where you live....
People have asked about making sure that resistor come from the same lot...
The resistor will be fabricated for us, that's why there is a 3 to 4 weeks delivery time, so they naturally be from the same lot.
grataku said:
This will be the LAST MEMO I am sending out.
We are getting dangerously close to the deadline that is in 24 hrs. At this point we have all the people we were supposed to get on board. We certainly would like to have more!
Let me remind you further that if you did not send me your address your personal email WILL NOT be considered as a VALID request.
A couple of people have not done so, yet.
I re-added the total from the wiki, and there are now 1074 requests for this, moving up to the 1000 price bracket.
Did you get my information alright?
--
Brian
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