DRV134 pcb

[regiregi22]

I have one question, I use to see that the input capacitor is usually placed before the resistor to ground, in this case 10uF and 100k.

I can see in your design that you placed the cap AFTER the resistor to ground. Is there any advantage or disadvantage?
Placing it before forms a high pass filter, how does it affect if placed after?

Regards,
Regi

 

[AndrewT]

Hi,
placing the resistor before the cap ensures that capacitor leakage is taken to Signal Ground. This avoids a DC offset at the input.

 

[peranders]

Regi, if you check the datasheet you can see that Vin consists of two inverting inputs which requires no pulldown resistor. Bias current flows from the output of A1 and A2 via the internal feeback to the "+" input.

The first resistor is only a pulldown so the cap won't be charged if the input is unconnected.

 

[AndrewT]

The first resistor is only a pulldown so the cap won't be charged if the input is unconnected.

the pull down resistor ensures the input cap is charged. Omitting the pull down resistor and disconnecting the DC coupled source allows the input cap to discharge, back to near zero volts across the plates.

If there is an AC coupled source, i.e. with DC blocking cap on the output, then omitting the pull down resistor leaves the interconnect hot at indeterminate voltage depending on the respective leakage currents and voltages in/at the two DC blocking caps.

 

[regiregi22]

Thanks teachers for your always helpful answers

 

[glorocks]

Will you be making these boards available for sale?

 

[regiregi22]

Yes,those boards are available at peranders website,look on google.

 

[Arick]

Bump once more. Any practical experience/opinions?

Hi,
I used 2 of your boards with LM regulators as a RCA to XLR converter on my B1, I had to use 2 independent transformers. When using the same transformer with 2 different power supply's there was a voltage difference between the grounds, when one of the boards was left "floating" (B1 or DRV134 board). If both where forced to be grounded to a star ground then it created noise. The only way we got out of this problem was to use separate transformers. Then everything worked fine!
Regards,
Eric

 

[regiregi22]

Hi,
I used 2 of your boards with LM regulators as a RCA to XLR converter on my B1, I had to use 2 independent transformers. When using the same transformer with 2 different power supply's there was a voltage difference between the grounds, when one of the boards was left "floating" (B1 or DRV134 board). If both where forced to be grounded to a star ground then it created noise. The only way we got out of this problem was to use separate transformers. Then everything worked fine!
Regards,
Eric

have you tried using 2 different power supplies that share the same bridge/smooth cap after the transformer?

 

[Arick]

No, I was not able to try this, because of the way the regulators where made. It would have been too much trouble modifying them.
Eric

 

[mrsavage]

Order four (4) DRV134 pcb's

I would like to obtain four (4) of your DRV134 Circuit Boards. Let me know
when they are available and how much they cost. Take care and thanks.

 

[aniket1131]

I am not able to get 2 small pcb's i.e.
1. DRV134 Balanced line PCB.
2. Voltage regulator board for the DRV134.

If you have these pcb's kindly let me know. If not, kindly help me in getting these pcb's

Regards
Aniket Salhotra