Mark Burnley

True Bypass With Relays (balanced)
« Reply #20 on: March 28, 2005, 02:35:56 PM »
Yes,

Use a resistor and 10 or 12V zener diode to drop the input voltage before the 7805- or even use a 7812 before the 7805! (they're cheap enough) Pre-regulation is useful in an on/off situation because the current draw won't be constant.

If you just use an input resistor to drop the voltage, when the relay is swithed off the input voltage to the regulator will rise to its full value. True, there is no dissipation within the regulator with no load current, but sometimes the actual voltage at the Input pin can be too large, and damage the regulator.

Mark
O_O tape is life O_O


True Bypass With Relays (balanced)
« Reply #21 on: March 28, 2005, 02:43:46 PM »
What if I just went with a 12V relay?

Doug

True Bypass With Relays (balanced)
« Reply #22 on: March 28, 2005, 02:48:42 PM »
Quote from: "Mark Burnley"
Yes,

Use a resistor and 10 or 12V zener diode to drop the input voltage before the 7805- or even use a 7812 before the 7805! (they're cheap enough) Pre-regulation is useful in an on/off situation because the current draw won't be constant.

If you just use an input resistor to drop the voltage, when the relay is swithed off the input voltage to the regulator will rise to its full value. True, there is no dissipation within the regulator with no load current, but sometimes the actual voltage at the Input pin can be too large, and damage the regulator.

Mark


So the 12V zener is there it keep it "conducting"? So that when you switch it off and it isn't loaded by the relay, the zener will still conduct? Does the zener go to the ground and the resiter in series? Should zener go before or after the resister? How did you pick 10ohm?

I have a mic pre psu that I could probably use the 48V and populate it so that it will spit out the control voltage.

Doug

dukasound

True Bypass With Relays (balanced)
« Reply #23 on: March 28, 2005, 02:49:37 PM »
Quote from: "Mark Burnley"
Yes,

Use a resistor and 10 or 12V zener diode to drop the input voltage before the 7805- or even use a 7812 before the 7805! (they're cheap enough) Pre-regulation is useful in an on/off situation because the current draw won't be constant.

If you just use an input resistor to drop the voltage, when the relay is swithed off the input voltage to the regulator will rise to its full value. True, there is no dissipation within the regulator with no load current, but sometimes the actual voltage at the Input pin can be too large, and damage the regulator.

Mark

I agree
I find this about min. and max. voltages:

7805    7-      25
7808   10.5-  25
7810   12.5-  28
7812   14.5-  30
7815   17.5-  30
7824   27-     38

True Bypass With Relays (balanced)
« Reply #24 on: March 28, 2005, 02:50:37 PM »
This is the comment that spawned by 1N4001, I am still not sure I understand. Are you talking about added new diodes, or using 1N4001 for 2 of the diodes already drawn on the schematic?

Quote from: "Mark Burnley"

regulator with two series connected 1N4001 diodes in the Common/0V lead connected to 0V.

True Bypass With Relays (balanced)
« Reply #25 on: March 28, 2005, 02:54:05 PM »
Cool..

I could totaly do the 12V if I can find a relay that works.

duka, what relay fits your layout? Does it come in a 12V format? What else do I need to looking for? Latching? DPDT? COIL?

Doug

mathflan

True Bypass With Relays (balanced)
« Reply #26 on: February 06, 2006, 08:12:29 AM »
Any news about the type of the Relay, is there a Reference number??

Re: True Bypass With Relays (balanced)
« Reply #27 on: December 20, 2011, 09:36:47 PM »
Hi everyone, just wondering if there is anything particularly wrong with using a 4pdt toggle switch instead of a relay bypass?

i realise from a signal routing point of view, that by having relays close to in/out xlrs may help reduce potential noise pickup etc, but is there any other reason such as contact quality, switching noise to take into consideration etc? I may be answering my own questions here, but 4pdt switches are pretty cheap to buy and would potentially seem more straight forward than constructing a relay bypass board. Thanks for any input on this.
Chris


 

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