Sifus,

How are you? I am looking for a anti-vandal switch with dual light capability. I found one anti-vandal switch here in lyn but it has only 1 color. Anyone know where I can find them?

Thanks a lot

have anyone build the sigma 25 linear psu b4?
i notice for the ac side there's no grounding. so the device does not need grounding?
http://www.amb.org/audio/sigma25/

this is single rail psu.

The other "rail" is the ground.

so is it safe or usable as it is?
or do i have to make it into dual rail?

Is your application single or double rail?

i just need a linear psu for my audinst hud mx 1. So i m not sure if i need single or double. any advise? Need it to replace the stock wallwart

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Added on April 22, 2011, 12:48 ami have also read that linear psu seems to be very inefficient, is that true?

This post has been edited by islubio: Apr 22 2011, 12:48 AM

If it runs at 24VDC, just get DC adapters from Teletron. (available at JP).

They use the same chip. The sigma25 is simply a LM7824. Teletron is the same.

Whether it's single or double is simple. Does the input have three pins? Or does it have two pins?

Linear PSU is inefficient but more than enough for amplifier purposes. Unless we're drawing hundres of watts of power(e.g. computers), otherwise linear all the way as it is less noisy.

ic so it all depends whether i wanna use 3 or 2 pins.
well i m from singapore so i will take a look at the shops here.
i don think i need 24vdc

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Added on April 22, 2011, 1:45 amthe dac takes 12-15V

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Added on April 22, 2011, 1:57 ambtw have anyone tried a ADuM4160 dongle??

This post has been edited by islubio: Apr 22 2011, 01:57 AM

i see on internet, Audinst HUD mx1 required 12-15v adapter, just buy any adapter with 12VDC 1A at JP, it will work ok, inside Audinst HUD mx1 already have Linear voltage regulator IC KIA278R12PI, it work same as 78xx as use in "The σ25 Regulated Power Supply", but technically KIA278R perform better than 7812. for better regulated voltage i think better find 15VDC 1A adapter

This post has been edited by MessO WreckO: Apr 23 2011, 12:35 AM

Those with 'R' are LDO voltage regulator,as the input supply is around 12-15v like you said.Technically,it's just normal LDO with on/off function.

is it hard to find opamps and bd adapter over here? wanna roll my dac amp but it seems gotta import

Hi,

This is my current project. I intend to use it as a headphone amp.

Has anyone used this topology before? I was wondering if there is anything that I should look out for.

Also, was wondering if this counts as class A.

Thanks


Attached thumbnail(s)

yes.. the output stage is class A operation... LM317 works as constant current sinking...

my previous project also use this output topology, but use transistor instead of op amp.. fed back to emitter


i think.. got mistake on this diagram.. check the R1.. "Adj" should be connected directly to "Out" and then tied together to R1.. R1 to gnd

This post has been edited by Bida Bing: May 18 2011, 05:02 PM

This is misleading,recheck again.

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Added on May 18, 2011, 5:15 pmClass A or not,depends on your amount of current sink and output load...

Anyway,output voltage of this kind of circuit

1)not  going to swing fully symmetrical,as the MOSFET  required a VGS of a few volts,
2)and due to VGS issue,DC output offset is present,
3)unless you got a high driving capability front end,use only low input gate capacitance MOSFET,such as the popular IRF610,the part number shown in the schematic is not recommended.


This post has been edited by Leolabs: May 18 2011, 05:21 PM

LM317 is easy peasy, but it's much better to use the same MOSFET as a current source. Just bias it with LEDs.

Amp in this configuration is definitely unstable. Need to have some gate resistors + compensation caps.

[quote=Leolabs,May 18 2011, 05:12 PM]
This is misleading,recheck again.

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Added on May 18, 2011, 5:15 pm

Ops.. you right.. sorry.. the connection already correct.. im already forgot the connection.. the project i construct last year just using breadboard...

yes.. right.. use irf610...

R3 should be coupled with capacitor to minimize output offset voltage...

need large heatsink... will run hot after 10 minutes play the music...

Just noticed about this circuit.. use split power supply... my project was use single power supply... and blocking capacitor at output..

i think.. this circuit wont work or will produce hi distortion due to Vgs of mosfet.. need to bias the mosfet..

This post has been edited by Bida Bing: May 18 2011, 10:36 PM

But won't the feedback of the amp compensate for the error in Vgs?

cos for now, the output of the op-amp is constantly a certain voltage.

P.S. got any reference so I can understand a bit more? Thanks

This post has been edited by sakaic: May 21 2011, 01:27 AM

hey guys i need help replacing my JBL bass2/Basswave amp. here's the speaker specs http://www.nodevice.com/images/sm/big/2008..._29/46742_1.jpg

any help would be great.. thanks.

What is wrong with the amp?

i bought the speaker for 20 bucks the amp damage beyond repair.. the twin speaker is ok tested already,,,

This post has been edited by runsing: Jun 1 2011, 11:34 PM