• These commercial threads are for private transactions. diyAudio.com provides these forums for the convenience of our members, but makes no warranty nor assumes any responsibility. We do not vet any members, use of this facility is at your own risk. Customers can post any issues in those threads as long as it is done in a civil manner. All diyAudio rules about conduct apply and will be enforced.

GB for DC coupled B1 buffer with shunt PSUs

Jump to Latest
#2,526
check the pin pitch grid is identical.
Double pole, change over (DPCO) is the same as double pole, double throw (DPDT)

The PCB accepts two rows of 5pins.
The 5pins are at 0.1inch pitch and the two rows are 0.3inch apart. Two of the pins (at one end) are not connected.
 
#2,527
Tea-Bag said:
It's been asked, this will be the production board for the Mesmerize. A different 2L weaked version with T mod, 2oz copper. It will cost more, so Salas and I won't celebrate by buying a Lotus Elise, more of a used Citron instead.😛
The only difference here will be that this version won't be prototyped. Minor variations should not require it.
Click to expand...

Please make sure to have 2 pads added for a 0.1 uF 5 mm cap at the output of the 7812 as this is a design error causing relays to malfunction. There is space enough between the output of the 7812 and the 2k2 resistor for the LED.

Also larger pads for the power LED would be useful as practically nobody will be able to use a LED soldered straight to the PCB since the PCB will be placed at the back of the cabinet/case as the design intended. Better enlarge the pads so Phoenix/Molex KK connectors can be used (or wires). Same pitch but slightly larger pads and slightly larger drilled holes.

Both very small effort, big gain.
 
Last edited:
#2,530
No reason not to use them at all. They are given as alternatives in the BOM. Exactly because 9240s are standard in many amps, that is why I included them in the BOM for when there are shortages. In other occasions they have been reported as more expensive. The parts ''stock exchange'' is on the loose it seems.
 
#2,532
It was current gain inadequacy of the realy driver NPN in few occasions in the evaluation of the first prototypes, it was reported back and remedied with the use of BC517 Darlington. That cap was another way to patch the oscilation of the normal NPN if it occured. We gave it the name of ''chatter'' back then. Was a classic collector to base Miller cap. Not across 7812's out. It was never reported ever again in the main release, people use the Darlington, and BC517 designation for the coil driver is printed on board too.
 
#2,533
OK, I solved it at that time by soldering a 0.1 uF cap at the output of the 7812 ( that needs a cap there anyway = good design practice). Afterwards I changed the relay driver to a BC517 just to make sure.

Two extra pads and a standard 0.1 uF cap are not that expensive. The same counts for the somewhat larger LED pads/holes which will only cost 0 $ or 0 Euro extra.

At least the muting situation (as suggested before) and the jumpers have changed for the better in the new version. The thicker copper tracks won't differ that much in this application.
 
Last edited:
#2,536
Hi Tea-Bag,

I'm coming in just under the wire here, but I'm not sure how many of which items to order. I'm looking to build a two channel preamp with input switching.

I presume this means I need 2 boards, but I don't know how many of the relays are required. If you can let me know, I'll send payment via paypal by mid-day tomorrow (10/24).

Thanks!
Eric
 
#2,537
Eric said:
Hi Tea-Bag,

I'm coming in just under the wire here, but I'm not sure how many of which items to order. I'm looking to build a two channel preamp with input switching.

I presume this means I need 2 boards, but I don't know how many of the relays are required. If you can let me know, I'll send payment via paypal by mid-day tomorrow (10/24).

Thanks!
Eric
Click to expand...

Hi Eric, if it's single ended stereo (not balanced) then you only need one board.
You need one relay for delay start up, and one for each input you want, maximum of 6, so 7 total for one board..
 
#2,539
AndrewT said:
check the pin pitch grid is identical.
Double pole, change over (DPCO) is the same as double pole, double throw (DPDT)

The PCB accepts two rows of 5pins.
The 5pins are at 0.1inch pitch and the two rows are 0.3inch apart. Two of the pins (at one end) are not connected.
Click to expand...

But I find the nominal operating current, coil resistance and the operating power is different between DPCO and DPDT. Will this affect the operation of DCB1?
 
You must log in or register to reply here.
Top Bottom