Salas hotrodded blue DCB1 build - Page 285

stajo · 3rd March 2013, 07:10 AM

Quote:

Originally Posted by mantha3

For the "take a +12V auxiliary line from there" How do I ID the spot on the PCB where you are talking about?

Maybe you could use your meters as power on led instead of the led, just lowering the current resistor a bit.

mantha3 · 3rd March 2013, 12:39 PM

Quote:

Originally Posted by stajo

Maybe you could use your meters as power on led instead of the led, just lowering the current resistor a bit.

I may have to... The bummer is that I already got the illuminated power switch.

Here is the tech sheet on the power switch... It looks like it does not pull much at all...

Illuminated Power switch

stajo · 3rd March 2013, 12:51 PM

Quote:

Originally Posted by mantha3

It looks like it does not pull much at all...

The button probably contains an ordinary LED and has a built in resistor for 12 V feed. 10-30 mA would be my guess. Do you feed the power on LED with that, and kept 2k2 resistor? Then I guess it doesnt light up the house? And you could measure the current by taking the voltage drop over the 2k2 res.

/Staffan

mantha3 · 3rd March 2013, 12:56 PM

I am leaning towards hooking up both the Illuminated power switch and the VU meeter board to this spot:

I do have a heat sink coming for the 7812... I am buying a kit from Teabag. Having the heatsink on the 7812 perhaps I can push having both the Illuminate power switch and the VU meeters? Salas mentioned this 7812 is the breaking point I think...

Salas · 3rd March 2013, 01:02 PM

The sink will give you more spare current leeway before cooking that reg chip. How much exactly I can only tell when having the sink's full spec.

stajo · 01:05 PM

To my knowledge a 7812 takes well over 1 A sinked. You see were you have gnd. Its the copper lane that connects the centerpin of 7812 and the power on LEDs cathode. Between LED and the 12 V output from 7812 output pin you have a 2k2 current limiting resistor.

Dont think the copper lanes are designed for 1 A tho, but that you wont need.

Staffan

mantha3 · 3rd March 2013, 01:09 PM

I think this is the sink Teabag sends with his kits:

Heat Sink Specs

mantha3 · 3rd March 2013, 01:12 PM

PS - Teabag has upped the capacitors on the kits to 10,000uf 35v from 4700uf 25v... Not sure if that added capacitance changes things..

stajo · 3rd March 2013, 01:16 PM

Quote:

Originally Posted by mantha3

PS - Teabag has upped the capacitors on the kits to 10,000uf 35v from 4700uf 25v... Not sure if that added capacitance changes things..

Not in this case but its a good thing for hotrodders who does 2*15 V trafos. 25 V is licking its limits there since its ripple on the ingoing rectified 21ish voltage. Sure it is 2 times 10 000 per rail? They will most likely be big.

Staffan

Salas · 3rd March 2013, 02:03 PM

Quote:

Originally Posted by mantha3

I think this is the sink Teabag sends with his kits:

Heat Sink Specs

It will rise 20c/0.5W. I would not ask the chip for more than 500mA on that sink with circa 20V raw dc in we got here.

3rd March 2013, 01:04 PM	#2846
stajo diyAudio Member Join Date: Jun 2011 Location: Stockholm	To my knowledge a 7812 takes well over 1 A sinked. You see were you have gnd. Its the copper lane that connects the centerpin of 7812 and the power on LEDs cathode. Between LED and the 12 V output from 7812 output pin you have a 2k2 current limiting resistor. Dont think the copper lanes are designed for 1 A tho, but that you wont need. Staffan Last edited by stajo; 3rd March 2013 at 01:05 PM. Reason: Yea, Salas posted when I wrote

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
dcb1 buffer with shunt reg.	merlin2069er	Swap Meet	0	3rd August 2010 05:25 PM
F2 and DCB1 parts selection - please advice!	DQ	Pass Labs	6	25th November 2009 03:20 PM
Y B Blue - how blue LED improves the CD playback	Peter Daniel	Digital Source	176	25th September 2003 07:40 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

3rd March 2013, 12:56 PM	#2844
mantha3 diyAudio Member Join Date: Oct 2010	I am leaning towards hooking up both the Illuminated power switch and the VU meeter board to this spot: I do have a heat sink coming for the 7812... I am buying a kit from Teabag. Having the heatsink on the 7812 perhaps I can push having both the Illuminate power switch and the VU meeters? Salas mentioned this 7812 is the breaking point I think...

3rd March 2013, 01:02 PM	#2845
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	The sink will give you more spare current leeway before cooking that reg chip. How much exactly I can only tell when having the sink's full spec.

3rd March 2013, 01:09 PM	#2847
mantha3 diyAudio Member Join Date: Oct 2010	I think this is the sink Teabag sends with his kits: Heat Sink Specs

3rd March 2013, 01:12 PM	#2848
mantha3 diyAudio Member Join Date: Oct 2010	PS - Teabag has upped the capacitors on the kits to 10,000uf 35v from 4700uf 25v... Not sure if that added capacitance changes things..