DIY Audio Projects Forum

found this on my hardrive im guessing the same calc can be used for the value of the pot and cap



nice if someone could rustle up a pcb layout maybe incorporated in the NP-100v12 Amp headamp circuit

Koog

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Head Amp On 555 Delay all in one
NP-100v12 - 12AU7 / IRF510 HeadAmp

Well, here is the delay circuit I used..... excluding the high voltage power supply.

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Hey guys

i put together a circuit based on a 555

the red led is the delay start indicator and green relay on

the delay is only short with the specified values around between 1-6 sec adjustable






Regards

Rupert

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Homebuilthifi Projects
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Head Amp On 555 Delay all in one
NP-100v12 - 12AU7 / IRF510 HeadAmp

Hi koogar

That looks fine and simple ...good work, thanks for sharing

I'm going to find out, how to make a "turn off circuit" to, because it's not fun only having a turn on circuit, as i've got now ( only half done ). Something is going to happen soon. If not possible, i'll go back to two switches, one for the supply and another for the headphone-output.

how can you adjust the time that it tankes to turn on
on the origlinal circut?

It's not easy to adjust the version i've made, but 680 - 1000 uF instead of 470 uF, should theoretical make the delay longer.

If you want an adjustable delay circuit, you should instead go for the shown version from koogar with the 555 timer turn on delay, there it's possible to adjust timing with the trimpot.

Hi Kramme

How did you get on with the off circuit how loud is the thump i have not build my NP-100v12 yet ? i was thinking of a 3 way switch on at the top with off at the bottom as it passes center it disconnects the headphone jack but i havent really looked into it or thought what type of switch on/off/on toggle or something any ideas ?

i refined the Delay circuit as i got more use to eaglecad and now includes and input for audio and a pcb headphone jack so its a one stop solution for headamps i have included the board files for eagle if anyone wants to tweek it also the schematic,etch file,component layout pdf

you can find the files here http://homepage.ntlworld.com/ruperthirst/Recent%20DIY%20Projects/Audio%20Projects/

the updated Schematic gives up to 55 secs of delay but this can be increased by changing the pot value.

heres what it looks like unfortunately the relay has not arrived yet or the trim pot so i ghetto soldered one to the bottom to test the prototype pcb design 100mm x 40mm.







on power up the led will illuminate till the timer runs out then will extinguish at which point the relay will turn on connecting the right and left channels in to the PCB headphone jack .
The board layout is designed for a Neutrik jack which are cheap but of good quality there are around £2 delivered on ebay

the 555 was rescued from a commodore plus 4 computer just for nostagia good thing is with this circuit is it will take anything from 5-18v its only dependent on what relay voltage you use remember to use caps of 25v+ though if anyone decides to hit the 18v end but since relays tend to jump to 24v after 12 this shouldnt be an issue.

i designed this with regards to the NP-100v12 headamp project so ill prob post something in there also

Thanks for reading my boring txt
Koog

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Homebuilthifi Projects
runawaybrainz.blogspot
Head Amp On 555 Delay all in one
NP-100v12 - 12AU7 / IRF510 HeadAmp

aaaw poor old computer

Well i managed to get a DPDT 12v relay and a 500k trimpot over the weekend from Maplins the relay was only £2 which is not a bad price for Maplins

got the circuit finished up and tested works like a dream with a good range of delayed on .

I was thinking of including a Mute and HP Socket switch header for later use.

Good thing is it would not take much tweaking to turn it in to a nice speaker on delay ,bigger relay, input/output tracks and some terminals or big solder pads.

Just wondering if i use a 556 IC (dual 555) i might be able to make a delayed off and on which breaks the relay connection before it shuts down the power




Cheers

Koogar

_________________
Homebuilthifi Projects
runawaybrainz.blogspot
Head Amp On 555 Delay all in one
NP-100v12 - 12AU7 / IRF510 HeadAmp

Interesting idea. Are you also getting a turn off thump?
Cheers

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