newbie builds ioaudio MK47 microphone

[innercityman]

Make sure you measure the drop and calculate power.

Not sure to understand... How can I do that ?

Gotta make sure you're decently lower than the rating of the resistor.

The 680R is a 5W and the 330R is a 10W

 

[Delta Sigma]

Voltage drop * current = power
Voltage drop / resistance = current

or simply voltage drop squared / resistance = power

http://www.sengpielaudio.com/FormulaWheelElectronics.gif

 

[innercityman]

Ok thanks,

the resistors I used are the ones in the BOM, but I'll replace them by metal chassis mount wirewound resistors that will for sure dissipate more heat and last longer.

 

[barbaroja]

I built the PSU with the Power Toroid: Triad VPT-230-110
Did build with the three 1K resistors and the 1K rheostat.
However, I am not able to adjust to 105V, it is always more, like 115V.
What change can I do?

Mains here is 120-126V

 

[Delta Sigma]

I built the PSU with the Power Toroid: Triad VPT-230-110
Did build with the three 1K resistors and the 1K rheostat.
However, I am not able to adjust to 105V, it is always more, like 115V.
What change can I do?

Mains here is 120-126V

Is your mic or a dummy load connected?

 

[barbaroja]

Is your mic or a dummy load connected?

Mic connected. Actually starts closer to 108 and as it heats up goes higher. With dummy load is pretty similar

 

[vinylwall]

Remove one of the 1K resistors and replace with a 1.5K chassis mount (Mouser 71-RE60G1501). Connect wires to the PCB, mount the resistor somewhere in the PSU and connect. You should be able to dial it in then.

 

[barbaroja]

Remove one of the 1K resistors and replace with a 1.5K chassis mount (Mouser 71-RE60G1501). Connect wires to the PCB, mount the resistor somewhere in the PSU and connect. You should be able to dial it in then.

I will do as per your suggestion. Thank you for your help.