Jan 21, 2013

Talema 10VA transformer board


All DAC boards includes supply part. It is enough to connect only power transformer. Here I offer board for toroidal 10VA transformer manufactured by Talema which has pins to the PCB and it has very small radiation of electromagnetic field to the neighbourhood. Board also includes set of fuses, power switch and terminals.

Circuit description

Circuit includes terminal X1 for connecting of power cord. Voltage goes over main switch S1 and fuse F3 to the primary winding of power transformer TR1. From the transformer goes two secondary windings over fuses F1 and F2 to the output terminals X2 to X4. Output winding S1 designated for positive branch is doubled for easy connection of S/PDIF decoder.

Schematics diagram


First we assemble power switch. We can also assemble small two pin connector instead of him and connect power switch on the chassis via wire. Next we assemble fuses and also terminals which first join them together. On the end we solder power transformer.

Component view

Printed circuit board

Board is designed single-sided with wide routes. It allow to create them in amateur conditions. I ordered it at small local company Kohout Spoj.





Except transformer are components easily available. Fuses are in variant to the PCB. It is also possible to buy sockets for them. Their value must be lower than maximum allowed current of the secondary windings for their safe break-in after short. Transformer 2x7V is usable for DAC with AD1565. For DACs with 12V voltage regulators like PCM1794A board we buy transformer with 2x15V secondary windings and for DACs with 8V supply we use transformer with 2x12V secondary windings. Informations about required voltage we can study on the concrete DAC page. 



Board is simple, nothing can be assembled reversively that it must work on the first power-up. We must be very careful to prevent electric shock because on the board is present line voltage! Though toroidal transformer radiate electromagnetic field much fewer than EI transformer that it will be better to not place them closely to the DAC board to prevent eventual interference.

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