Relay Board Power Questions

[turtle441]

This seems like a silly question, but I had to pause as I was reading through the Hoffman amps store site ,so I'm asking.  I'm currently working on an amp where I need power supply for a relay on one side of the chassis, the actual relay on the opposite side.  So the split boards available in the store are perfect for my needs.  However, in reading the relay information page,  (http://el34world.com/projects/relay_switch.htm) I got confused.  He lays out a number of circuit designs without a voltage regulator, says that only the one with the half wave rectifier and artificial center tap gave enough voltage to run a relay and  an LED.  But, then, last schematic (with the voltage regulator) says it was putting out enough to run a couple of relays and LED's.  So, I guess, my question is, if I run the power board off of my heater tap and run an LED parallel to the relay (with appropriate resistor, of course), will that work?

Secondary question: Has anyone measured how much power the relay board set-up pulls?  (I'm sure the wiggle room in my PT is more than enough to cover this, but I hate leaving those sorts of things to chance.)

[sluckey]

The VR chip will supply 1A current with proper heat sink. The relay has a 5 volt coil rated at 40ma (.2 watts) so that's 1000/40=25 relays per VR chip. That's about how many relays you could energize simultaneously. Just be conservative and don't use more than 10 relays per VR chip.

Driving one or two relays and one or two LEDs from a typical filament winding is trivial. I'd just go full steam ahead.