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Old 5th November 2012, 04:10 PM   #641
Renron is offline Renron  United States
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I'm thinking of getting my face plate engraved with the different (6) input labels.
What have other people used ?
Tape (does anyone use tape anymore?)
Console (Xbox, PS3,Wii)

Thank you,
"If it doesn't work properly, hope it catches on fire"- Nelson Pass @ BA3
"I fired up the prototype. Literally." The Prophet Pass.

Last edited by Renron; 5th November 2012 at 04:16 PM.
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Old 20th November 2012, 05:34 PM   #642
L3o is offline L3o  Germany
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I just finished my Buffer and I love it. As next step I would like to build up a lightspeed attentuator to replace my Alps Pot. I'm just not fully sure how to connect the Buffer to the Lightspeed Attentuator board. Anyone who has done it before and can give me some advice? Sorry I'm quite a noob regarding these things...

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Old 20th November 2012, 07:47 PM   #643
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The output of lightspeed is actually identical to a potentiometer.
Just check the output of lightspeed and connect it as a plain pot
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Old 20th November 2012, 08:05 PM   #644
Marra is offline Marra  United Kingdom
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Are you going to use a seperate power supply for the Lightspeed or do you want to tap off the Mezmerize pcb?
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Old 20th November 2012, 10:17 PM   #645
L3o is offline L3o  Germany
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@Marra I'm going to use a sepeate power supply for the lightspeed.
@dimkasta Okay, but what to do with the third contact? Lightspeed has ground and signal, but how to deal with the third one on a normal potentiometer (2x connectors to resitance material 1x wiper connector). Not sure how to handle that part on the Buffer Board.
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Old 20th November 2012, 10:35 PM   #646
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Which lightspeed do you use? Uriah's?

Imagine the two LDRs on lightspeed as the two parts of the pot

"Signal in" is the front of the Series LDR. "Signal out" is its back.
"Signal out" is also the front of the shunt LDR, so imagine it as the wiper of a pot. And the back of the shunt LDR goes to ground or RCA return/shield.

Last edited by dimkasta; 20th November 2012 at 10:47 PM.
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Old 1st January 2013, 03:22 PM   #647
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Hi Gents, happy New Year,- hope i am in the right place???- I have a word…HELP!!

I have built my first project a Memorize (if you can read a London Underground map you can read a circuit diagram right?)—it lights up (hooray!)- But it’s not well!!

Having populated the board (Except for the BC 517—can’t get one in this town!) checked all transistors and cap orientations and all links are in (or bridged with 2 x 300 ohm resistors for the 5 v relays I have in.)

I have matched the LEDS up quite closely and I have tried to match up the four 2SK470BL using a battery as gleaned from the forum. (The information not the battery!)

I have wired it up and turned it on to find I have a all LEDs lit (Hooray!)- But the two IFRP240 gets quite hot,
On The other side the two IFRP9240 get a little warm but nothing like the two IFRP 240 (I can touch them for around 20 seconds, so it’s less that 50 degrees?)

Also I have used 5 volt relays (only ones I could get) and used 2 x 300 ohm resistors across the link
But still get 11. 9 volts at the switch (between the switch earth and selected relay pole on the switch) the 300 ohm resistors don’t seem to do much (should it be a 600 ohm pair here?)

The salient points are : Transformer is 50 V/A 2 x 12 volts with the “0v” wires tied together for a “faux” centre tap unloaded the AC voltage is 14.3v and 14.53v (AC) but I thank that’s fine?

II get: across the two 68 ohm resistors I get 1.80V on the IFRP9240 side-
and get 1.6 v on the IFRP240 side

On the “3 pads/test points” with 0v in the center I have +10.75 and -10.12 respectively (not to bad?)
But I think I am sinking more current on the IFRP240 side despite sticking to the design?
(The only difference I have is the BC 550 was replaced by a BC546C (but according to the data sheet for that device they are similar enough?)

I can’t yet check the DC offset till I get a BC 517—or is there a work around for this?

To be honest I am not sure where to go from here or where to measure, any ideas boys?—sorry for the long post.


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Old 1st January 2013, 05:42 PM   #648
Salas is offline Salas  Greece
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Your PSU voltages read good. About the voltage drop on the CCS resistors there is not much difference when divided by their value between sides. I hope you got no oscillation on the negative side, which is not too easy to get on a given proven layout. Are there any sinks? Use another 550 or 546 to populate the 517 place. BUT solder a 100nF capacitor between its collector and base pins underneath the board. It should work activating the output relay without mechanical chatter. Then you will be able to have output and see about DC offset. Happy new year!
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Old 2nd January 2013, 10:13 AM   #649
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Hi Salas,

Thank you for the timely reply, so its not so sick

I will do the necessary with a BC 556 and get back to you, cheers boss!


Johnny --Happy new year to all---
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Old 3rd January 2013, 06:38 PM   #650
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Hi Salas,

the trick with the BC 556 and cap worked very nicely, about 5 seconds and a nice "click" ta! for that.

With regards to the DC offset, its in the mili volt range but is jumping around (or so my volt meter tells me) when measured with 0v at the common earth and pos probe on the left/right channel output pins (i have installed a "molex" type socket)
but is very quite (no noise in fact) when applied directly to my Fostex 206E speakers, one channel is OK gives the same out volume as in so it unity gain?- sounds nice to!!

The other channel is very weak, can hardley hear it (i have acrapply 50 K ohm alps pot on just now for testing, will change when funds allow)

I dont know if the way to go is to buy some matched transistors (the IFRP 240/IFRP9240 and 4 x matched smaller ones from a very nice gent on this forum) , but i guess if the "normal sounding " side is Ok i could make A/B comparison checks and do it that way? (that sounds logical to me!) - also must adress the 12 v on my 5 v relays-- 2 x 600 ohm resistors required??

Cheers johnny
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