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PostPosted: 01 Nov 2010, 17:06 
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Joined: 31 Dec 2008, 15:34
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Last news from here:

( can't get my own versus of the delay relay "turn off" problem, out of my head ).

I were talking with a friend ( Asger ), he and i got that persuasive k.i.s.s idea, to add a simple diode ( BYW29 ), only for the PS + to the amplifier and a capacitor among 1000 - 4700 uF, large enough to make a hold of the amplifier circuit, while the delay relay were turning off. Well, i've tried to implement this to my own delay relay, but i didn't work. It actually made the whole thing worse, with an even higher spike, when turning off. :down:

Offcourse a voltagedrop among 0,5 V over the diode was a fact, but if it had worked, i wouldn't have seen it as a problem. Okay, it was worth a try, to solve the "turn off" problem.


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PostPosted: 01 Nov 2010, 17:58 
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Another interesting circuit.

Image

or what about a tube solution, with a "6NO30 Thermal Delay Relay" :mrgreen:

Image


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PostPosted: 02 Nov 2010, 14:17 
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When playing around yesterday, i came on this "three component" variant, delay relay, which actually works. I have tried four different 6J5GT tubes of mine ( both glass and metal housing ) and they all got delays between 12 - 14 sec. with a 6,5 VDC PS. If PS is raised to 6,8 VDC the delay is around 5 - 7 sec. I see this as a fun delay relay, to share with all of you. :mrgreen:

The way it works: When feeding the filament, the resistance ( measured ) between anode/plate and cathode will change from OL. to around 1K ohm, this will activate base of the transistor which will open collector to emitter and lead current, this draws the coil of the relay. Simple ? = yes :wizard:

To find a workable tube for this purpose, supply the filament while you measuring with an ohmmeter between the plate/anode and the cathode. With measurements in the low-range Kohm, it's possible to get an ordinary small signal transistor ( ex. BC557/558 ) working. If measurements are in the high-range Kohm, a Fet transistor can be used instead.

I've tried other triode tubes ( ex. 12AU/AX/AT7 ) with success 8-) I guess some of you can find usable tubes in the junkbox. :thumbsup: Let me hear, if you're trying this construction ...thanks !

Illustration of the full monty.

Image

Wanting a 30 sec. delay ( for what purpose ? ...hehe ), use an EL84 tube. Instead of plate/anode use grid 1, like illustrated below.

Image


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PostPosted: 02 Nov 2010, 15:39 
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EDIT: For some tubes use the grid instead of plate/anode.

( In all shown examples, what we see is tubes acting as diodes, combined as resistors ).

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PostPosted: 02 Nov 2010, 22:36 
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Joined: 20 Oct 2010, 22:14
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Hello Kramme,

Glad to be of any help, am attaching a working ckt from a 24vac input , I adjusted some values (from thin air)for the 12vac-but not benched yet.Speaker turn-on delay is designed mainly to delay connecting the speakers to the amp, turn-off should be instantaneous to avoid the same "thump" , in transistorized amps.

I'm from Baguio City, Philippines and just about to integrate a valve amp just for the fun of it- given time . Also attaching a pic of collected parts. I have the OPT but no taps for the screen grid, I don't know if I can use them on the SIPP configuration using 12ax7 or 6sn7 preamp and 6L6 output.

I believe there is no degradation using diodes for rectification and 3 pin regulators as current source.
Attachment:
tubeKit.jpg

Noelm


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PostPosted: 07 Nov 2010, 08:55 
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Joined: 17 Apr 2010, 16:07
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Location: Huddersfield ,West Yorkshire,UK
The delay tube thing looks interesting idea and in keeping with the amp .

I have not had much time to play around with my 556 idea i used my delay circuit x2 and i have 2 timers running on the 556 its just getting my head round the shut down bit on the other side of the 556 after about 6 diff simulations my brain gets fried and i loose track of any progress :P

anyway i decided to go ahead with the current design in my prototype amp and any revision will make it into the next prototype as i will prob end up moving some stuff around anyway :coffee:


koog

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PostPosted: 08 Nov 2010, 18:50 
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Joined: 14 Oct 2008, 17:35
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Location: Dartmouth, Nova Scotia
Now that is the true a true simple delay circuit, for those people that must have an all tube amplifier, or just to show off their solid state project..... I bet that would get some one many questions from many diyers at an audio show. :P

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PostPosted: 29 Apr 2012, 10:26 
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Joined: 16 Mar 2012, 11:15
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Location: UK
Big thanks to Koogar for the 555 delay circuit and the eagle files. I've just built mine this afternoon and it's a cracking little circuit. Easy to make using the toner transfer method and only as complicated as necessary.


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PostPosted: 08 Aug 2012, 15:43 
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Joined: 18 Jul 2012, 17:45
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Maybe I managed to make a turn off delay on the amp, now no boom on the turnoff (still testing). The circuit used is in this site:http://home.cogeco.ca/~rpaisley4/LM555.html.
Redone the pinout to work properly.
Image
The amp in the LOAD conectors, X6-2 are positive. In 12V X5-2 is +.
You must use the headphone delay with since de relay will disengage the audio out at the moment the power are off and the circuit will power up the amp for a few seconds more... use a separate contact of the switch to turn the audio delay and this circuit on. If someone with more knowlegde see something wrong please warn us before some damage are made.
Cheers.
Austin.


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PostPosted: 02 Nov 2012, 01:31 
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Joined: 31 Oct 2012, 09:10
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Hi guys,

This is a noob question, on the 555 delay timer is there a reason you don't just use a single pole relay on the headphone ground line?


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