Mezmerize DCB1 Building Thread

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#2,121
A1. 2U should be enough. The base plate has enough mass to cool a MEZ without extra sinks even.

A2. They are test points right on the regulated rails. Middle one is GND. You don't want to risk interference from utility units or a motor there.

Congrats for your build up to now. You are welcome.
 
#2,122
Unfortunately I started this project about a year ago. Going back over everything I noticed the 220K, 220R and 1M resistors are supposed to be super quality parts. You will notice in the pictures that I have Vishay Dale resistors. Will these be ok or should I swap them out for something else?

Still learning but learning enough to know to ask the question.

Thanks!
 

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#2,128
Salas said:
No need to change any resistor values.
Click to expand...
Salas,

Thank you. I appreciate the input. Once I got started building I find that I am enjoying it immensely and getting to learn a little about something new.

At the same time I want to extract every ounce of performance out of these efforts and researching different components at least starts to give me some insight as to why one component is better than another.

Regards,
 
#2,129
Salas said:
A1. 2U should be enough. The base plate has enough mass to cool a MEZ without extra sinks even.

A2. They are test points right on the regulated rails. Middle one is GND. You don't want to risk interference from utility units or a motor there.

Congrats for your build up to now. You are welcome.
Click to expand...

So what are the best options for additional power requirements within the same chassis to power a motorized volume control, latching relays etc? It seems to me that any kind of the little ebay power supplies would be far too noisy to put in the same chassis. Am I just better off getting another Mez board and using the power supply section of that with a smaller transformer? I looked at the super regulator and linear audio silent switcher on the diyaudio store and those do not accept mains voltage.

Thank you
 
#2,130
A pot motor's PSU/driver is not critical as long as it won't have a microcontroller that stays on all the time. Same for any IR remote and/or display circuitry PSU. Just give them their own transformer and don't associate them with Mez's signal ground if possible.

Mezmerize's input selection relays are already powered by an onboard LM7812.
 
#2,131
Matching LED's

Hi Salas and all others!
Sorry for this one:
I've been searching on advice/guidance on matching the LEDs. I'm lost a bit 😱
Is there something like a step-by-step-guide? How do I measure/match that stuff?

Again, sorry!
and thanks many times
david
 
#2,134
As Tea-Bag points out the red Knightbrights are well matched. I went through the matching process myself just because I am trying to learn and wanted to understand the process. I soldered a couple of breadboard leads to a 9v battery and made a simple circuit using a resistor (I believe it was 1.2k) in series with the LED. Light up the LED and measure the voltage across the LED by connecting your voltmeter across the legs of the led. I wrote the voltage on a piece of paper and taped the led next to the measured value. Do this for a bunch of leds and when you get enough of one value, you are good to go. If you need something more visual check out this build DC-Coupled B1 Buffer Build Scroll down until you see the led test section. Have fun!
 
#2,136
LED matching...

Hi Salas and friends


So, I'm measuring my LEDs with a series of 8 1.5V AA batteries...
Serie 1: 1.913 V - 1.917 V
Serie 2: 1.92x V - 1.94x V
Serie 3: ~ 2.07 V

I then tried a 9V battery. They measure lower. Of course.
Should I stick with the 12 V?

Then, I make the selection to come as close to 10 V
And, since they're all above 1.8 V, I'll get something like 9.575 V (5 * 1.915). Select the highest values or look further?

And as a last question, I just read this post here:

Salas said:
Plus you should measure them as a bunch of five driven by their associated JFET to go in the board under 0.6V VDS in IDSS mode. If you want absolute predictability. It amounts to no performance gain is my 2C. Aesthetics.
Click to expand...

Matching LED individually is obsolete? Can somebody guide me through this please? 😱

Thank you very much!
david
 
#2,137
Different test voltages with same test resistor naturally going to provide different mA and different VF. Stock to 9V.

Individually is not obsolete as a method given the IDSS of the JFETS driving string of fives is comparable.
 
#2,140
Heat sinks sufficient

Good evening

I'm building..
But because I have the bad habit to question way too much things I decided earlier, I have a question on heatsinks.
B1 seems to work with the Mosfets attached to the bottom of the chassis.

I'm going 200mA though. I have similar heatsinks as Neville displayed in the post below (or the Image is here), I wondered how little mass they have when I received them.


Salas' cool answer suggests it is ok, so, is it?

thanks!
david

Salas said:
Congrats...
Click to expand...
 
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