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Old 29th September 2009, 07:35 PM   #1011
Salas is offline Salas  Greece
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Quote:
Originally Posted by AndrewT View Post
Is there any positive feedback from the relay drive to the control signal input?
As the transistor starts to send current through the relay the positive feedback increases the speed of activation and ensures a hard switch on signal without chatter.

Without feedback the signal rises slowly and if the source impedance feeding the relay is high the current falls as the relay starts to pull in and falls open again.

This problem will be alleviated by using lower current, higher voltage relays. 5V need lots of current, 24V need tiny current by comparison.
Our solution so far is a 0.15u mylar or ceramic capacitor from collector to base of the relay pulling NPN. That makes it work normally.
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Old 29th September 2009, 07:38 PM   #1012
Salas is offline Salas  Greece
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Originally Posted by Ian444 View Post
PCB was in the mailbox this afternoon when I got home from work Some progress was made as far as filling the board. Tomorrow I may get it hooked up with some music.

It is obvious that crt has layed out more than a few PCB's in his time, and has his preferences for pad and hole sizes. The quality is good. It is well laid out and this makes it easy to build. I hurried it up a bit so I could get back to you guys who are waiting on the last of the proto builders, so a decision on a go-ahead for PCB production can be made soon. I remember Salas saying something about LED sizes, now I understand, 5mm LED's will not fit flat on the PCB.

No relay chatter, it turns on after about 3 to 4 seconds, the part number of the one I am using is GP-212 and the manufacturer is Goodsky. I am not using an LED in the cct near the timing cct for the relay yet. I put a 100nF cap in the cap position next to the LM7812, i.e. the unmarked cap on the input to the LM7812, and the LM7812 manufacturer is STI. The AC input from the 60VA 15-0-15 tranny is 16.5 and 17.4V, the DC out from the rectifier is 23.8 and 23.6, the regulated DC is -9.74 and +10.04, the DC offsets are -1.1mV and -0.5mV. Hope this info helps. Time to eat and go to bed now...

http://i198.photobucket.com/albums/a...60/Buffer1.jpg
http://i198.photobucket.com/albums/a...60/Buffer2.jpg
Very nice indeed. Your transformer sounds like a 2X17VAC to me, so help the CCS Mosfets with some little sinks.
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Old 29th September 2009, 07:49 PM   #1013
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Quote:
Originally Posted by kannan_s View Post
Good news on the Chattering relay problem - seems the 7812 quality is the reason. I changed the 7812 ( ofcourse my original build had filter 0.1uf Cap as somebody had asked me about it) to JRC brand as the original one was from some unknown make - the chattering is gone - no need for cap

I think Tea Bag also can try changing his 7812 to check this out.

kannan
Thanks Kannan, I've added your input to the BOM V3.6.
Same regulator reference L7812ACV from STMicroelectronics, ref for Farnell's modified (L7812CV in V3.5), Mouser's one was right confirmed by BillyK.

Last edited by korben69; 29th September 2009 at 07:52 PM.
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Old 29th September 2009, 08:12 PM   #1014
Tea-Bag is offline Tea-Bag  United States
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Quote:
Originally Posted by kannan_s View Post
Good news on the Chattering relay problem - seems the 7812 quality is the reason. I changed the 7812 ( ofcourse my original build had filter 0.1uf Cap as somebody had asked me about it) to JRC brand as the original one was from some unknown make - the chattering is gone - no need for cap

I think Tea Bag also can try changing his 7812 to check this out.

kannan
I used this one.
512-LM7812CT
I typically buy Fairchild components......
I will order one that works when I get another order to mouser going.
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Old 29th September 2009, 08:18 PM   #1015
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Quote:
Originally Posted by woodturner-fran View Post
Have we moved from the google spreadsheet to the new wiki system here?

Fran
Fran, I have no intentions of using the new Wiki system for this group buy.
Once the qoute comes back for roughly current quantities, price will be set and then it will quickly move to pay-up time. I want to put the order in for the PCB's on October 12th. So last day to pay will be the 11th. Price will be set hopefully in the next few days.

I want to get this GB moving along. We'll decide about latecomers later on.
Probably another small quantity next year may be warranted, assuming internal selling of extra's occurs first.
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Old 29th September 2009, 08:27 PM   #1016
billyk is offline billyk  United States
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Quote:
Originally Posted by Tea-Bag View Post
Fran, I have no intentions of using the new Wiki system for this group buy.
Once the qoute comes back for roughly current quantities, price will be set and then it will quickly move to pay-up time. I want to put the order in for the PCB's on October 12th. So last day to pay will be the 11th. Price will be set hopefully in the next few days.

I want to get this GB moving along. We'll decide about latecomers later on.
Probably another small quantity next year may be warranted, assuming internal selling of extra's occurs first.
++
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Old 29th September 2009, 08:28 PM   #1017
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Quote:
Originally Posted by Tea-Bag View Post
Fran, I have no intentions of using the new Wiki system for this group buy.
Once the qoute comes back for roughly current quantities, price will be set and then it will quickly move to pay-up time. I want to put the order in for the PCB's on October 12th. So last day to pay will be the 11th. Price will be set hopefully in the next few days.

I want to get this GB moving along. We'll decide about latecomers later on.
Probably another small quantity next year may be warranted, assuming internal selling of extra's occurs first.
Good move - let us get going with this as changing it to wiki will add another confusion among the participants
kannan
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Old 29th September 2009, 08:42 PM   #1018
billyk is offline billyk  United States
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If anyone is counting... Salas announced the boards 2:23 PM EST on 27, August. When the order is placed on the 12th that will be 6.5 weeks from board to proto to GB order. Could that be a record?
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Old 29th September 2009, 08:46 PM   #1019
Tea-Bag is offline Tea-Bag  United States
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hey, I don't f$%k around.
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Old 29th September 2009, 08:56 PM   #1020
Salas is offline Salas  Greece
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Got the PCBs from Tea-Bag today. The quality is MUCH better than our quick amateur photos can capture. They are like plexiglass in reality. Thick and shiny and take a negative film like dark brown pearl gloss when passing light. Pitch black normally. The silkscreen is sharp and the pads perfect. They remind of an ASUS board. Kudos to Crt and Tea-Bag.
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