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Old 3rd May 2010, 01:43 AM   #1401
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It's good practice to connect it to your enclosure for safety. The last thing you want is a "live" chassis should something happen. (i.e. wire nut falls off - bare wire lays against chassis... you get the point) The equipment we build should be properly fused and grounded
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Old 3rd May 2010, 02:43 AM   #1402
Salas is offline Salas  Greece
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Quote:
Originally Posted by regiregi22 View Post
hello,

Salas, I have a question for you or anybody who could help me. It is about the delay start circuit of the DCB1. If I put an smaller capacitor (I actually have a 100uF one) can I make the relay to mute the circuit sooner? I mean when you turn it off.

I need the relay kick in it a bit earlier for a Lightspeed attenuator experiment I am doing with the buffer.

Thank you very much for your help, guys. I really appreciate it.

Regards,
Regi
There is a 10k resistor that discharges the RC. Making the cap smaller will engage the relay at turn on sooner too. Its OK as it is, so I would experiment with a smaller one than 10k to drain the system faster, so to disengage faster. Haven't actually tried that though, because the disengage time is OK. That ''bleeder'' resistor will ask more current from the 7812 during normal operation, so you better use a little sink for it.
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Old 3rd May 2010, 10:13 AM   #1403
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Originally Posted by Salas View Post
There is a 10k resistor that discharges the RC. Making the cap smaller will engage the relay at turn on sooner too. Its OK as it is, so I would experiment with a smaller one than 10k to drain the system faster, so to disengage faster. Haven't actually tried that though, because the disengage time is OK. That ''bleeder'' resistor will ask more current from the 7812 during normal operation, so you better use a little sink for it.
I have placed a 470uF cap in parallel with the 100uF. As planned, start time rises up to 1 minute. But shuting down time remains the same, 1 second. I will try changing the resistor...
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Old 3rd May 2010, 10:32 AM   #1404
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The next thing I tried is to change the 10k res. (still having 100uF). Measuring it at the board gives you 2.3 kOhm because is paralleled with other things. By placing a 1k res. in parallel with the 10k (thus making an equivalent of 0.9kOhm), it gives a resultant resistance of 0.7kOhm.

but the strange thing is that it does nothing to the delay times. It continues turning on and off at the same times. What is wrong, Salas?
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Old 3rd May 2010, 10:49 AM   #1405
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Don't know, haven't tried to shorten disengage time as I told, seems the main filter charge isn't draining enough any faster no matter the heavier bleeder.Try less than 47k R to C this time, parallel one resistor and see what happens. Why you want super fast release? What is it in danger?
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Old 3rd May 2010, 11:41 AM   #1406
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I am going to integrate an LDR volume control. It is supplied by +5v, so I am going to tap +17v from the main filter capacitors to a +5v regulator. The problem is that LDR volume control start to misbehave when they have less voltage than 5v. As it goes down, there is a point where it sounds at max volume, something REALLY disgusting.

So I have two approaches:
-To put a BIG capacitor after the 5v regulator, so the LDR will keep being supplied a bit longer.

-To enshort the relay shut down time, so it doesnt have time to get a lower voltage than 5v, thus closing the relay before it reach that maximum volume fault.

-Wait to have the LDRs delivered at home and check if maybe I am too paranoid, and the 1 second it actually takes to shut down is more than enough. By looking at how the voltage supplied by the main filter caps decreases when I shut it down, my bet goes for this option. The DMM display is not fast enought, but I think that it still says 7v in the main filter caps when I hear the relay closing. Then it goes down to 2v.

Is has the same problem when starting up, but I already have a 10 seconds start delay on my DCB1, so half of the problem is solved. I will try to change the resistor you say. I may solve that just by adding a big cap after the 5v regulator, but it has became a curiosity matter. I NEED to be able to tweak things
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Old 3rd May 2010, 01:58 PM   #1407
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Quote:
Originally Posted by regiregi22 View Post
I have placed a 470uF cap in parallel with the 100uF. As planned, start time rises up to 1 minute. But shuting down time remains the same, 1 second. I will try changing the resistor...
If someone are interested in larger time delay, here is my experience.
Yesterday I make delay relay for tube preamp, part of amb's Epsilon 12 schematic. This is very similar to DCB1 time delay, except it use 1N4148 darlington, instead of two npn's.
I use 1M resistor and 470 uf cap and get about half minute delay, adding second 470 uf in parallel give about 1 minute delay. Adding or removing 10K not make big change (amb's shematic are without it).
It powered from 12V regulated, relay used - TYCO ELECTRONICS MT2-C93402
TYCO ELECTRONICS|MT2-C93402|RELAY, PCB, DPCO, 12VDC | Farnell Latvijas Republika
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Old 3rd May 2010, 08:05 PM   #1408
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Originally Posted by william2001 View Post
It's good practice to connect it to your enclosure for safety. The last thing you want is a "live" chassis should something happen. (i.e. wire nut falls off - bare wire lays against chassis... you get the point) The equipment we build should be properly fused and grounded
Thanks, I'll run earth ground to the chassis.

I've got 750ma slow-blow fuse installed, if I remember correctly, that is what was spec'd out.

Thanks,
JG
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Old 4th May 2010, 12:12 AM   #1409
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JG, have you had a chance to listen to it yet? I always enjoy reading subjective opinions.

I've got some parts on the way from Parts Connexion, Vishay MKP-1837's to replace the LED 'lyctics (.2 uF each position), and new PRP resistors (33,33,27) to run the heavy shunt current. Found some thick aluminum bars to replace the puny heatsinks currently in there, hopefully it will be enough. I'm going to yank the Takman carbon films out of the Hypnotize and replace with the PRP metal films, leaving Takman's in the Mesmerize. I can compare one DCB1 with the other just by swapping harnesses inside.
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Old 4th May 2010, 12:33 AM   #1410
Salas is offline Salas  Greece
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Will be interesting. Lets see if the films tone marry well with LSPD tone mixed already.
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