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Author Topic: 18w minimalist  (Read 13386 times)

guitarfreak666

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Re: 18w minimalist
« Reply #15 on: March 12, 2012, 12:52:49 PM »
awesome advice. i have the power suply almost ready, but how do i discharge the caps????

phatt

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Re: 18w minimalist
« Reply #16 on: March 13, 2012, 05:26:13 AM »
If your power supply is setup correctly with bleed down resistors then you won't need to worry.

If not sure then bridge them with a low value resistor,, say 500 ohms.
Use DMM to check how much Voltage is present on the terminals.

Once the DCV is below about 70 Volts it's fairly safe and unlikely to kill you but ideally you want to see close to Zero.
Phil.

guitarfreak666

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Re: 18w minimalist
« Reply #17 on: March 13, 2012, 06:35:39 PM »
so across the caps i put 500k resistor? how much watts should the resistors be?

phatt

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Re: 18w minimalist
« Reply #18 on: March 14, 2012, 04:10:43 AM »
100 Ohms~ 500 Ohm. Not 500,000 Ohms ,,, as you will be waiting a fair while to bleed the voltage. Winky.

Use 1 watt or bigger,, the lower the R value the hotter it gets while holding it,,, but then you should not be holding it with wet fingers in bare feet?????? winky.

If inserting these into a build THEN you use 200k or bigger.

Bigger just means it bleeds down slower and does not load the supply while running.
Normally a PSU in a valve Amp will bleed down in about one minute But wise to check with meter if you are not sure.

With no bleeder setup they can stay charged for quite a while.

You can of course just short the terminals with a screwdriver but it will likely shorten the life of the Cap.  Not recommended but I admit to doing such things when in a hurry. :-[
Phil.

guitarfreak666

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Re: 18w minimalist
« Reply #19 on: March 14, 2012, 02:22:10 PM »
id like to built them in, since i probably will do a couple  of mods.

guitarfreak666

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Re: 18w minimalist
« Reply #20 on: March 28, 2012, 09:14:57 AM »
i have most of the parts, just waiting for the pt, but could any of you tell me how i could put a 3band tonestack in this amp?

grtz

J M Fahey

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Re: 18w minimalist
« Reply #21 on: March 29, 2012, 04:14:51 AM »
Copy some similar Fender amp, which has bass/mid/treble controls and a similar tube setup.

erokit

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Re: 18w minimalist
« Reply #22 on: April 01, 2012, 01:10:22 AM »
There used to be forum 18-watt.com. The builder of Gabriel amps, Gabi Bucatereu was an active contributer. He is extremely helpful and enthusiastic. He will love to help you out.

guitargabi@gmail.com

Tell him erok sent you!
« Last Edit: April 01, 2012, 01:14:56 AM by erokit »

guitarfreak666

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Re: 18w minimalist
« Reply #23 on: April 01, 2012, 09:14:34 PM »
i cant find a transformator with 215 on primary, if i use a 230, what value of resistor should i use to drop the voltage?

J M Fahey

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Re: 18w minimalist
« Reply #24 on: April 01, 2012, 09:35:20 PM »
Apply Ohm's Law.

guitarfreak666

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Re: 18w minimalist
« Reply #25 on: April 01, 2012, 09:41:36 PM »
i know how it works but i cant seem to make the formule work to calculate the value of the resistor

J M Fahey

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Re: 18w minimalist
« Reply #26 on: April 01, 2012, 09:48:51 PM »
You need to provide the current value first.

guitarfreak666

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Re: 18w minimalist
« Reply #27 on: April 01, 2012, 10:18:02 PM »
the problem is that i dont know how much the current will be

phatt

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Re: 18w minimalist
« Reply #28 on: April 02, 2012, 09:22:12 AM »
i cant find a transformator with 215 on primary, if i use a 230, what value of resistor should i use to drop the voltage?

Hum?
Do you intend to drop the *Primary voltage* via a resistor?

Phil.

guitarfreak666

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Re: 18w minimalist
« Reply #29 on: April 02, 2012, 02:50:38 PM »
no, i will use a transfo with a bridge rectifier and then let the voltage drop to 305v(the first voltage on the schematic) but i dont know how much current it will draw. could i get that info by the voltage drop across the second resistor, then i could calculate it.