relay assistance

[joesatch]

i normally use 12v relays but in this case i'm using a 5V relay. The relay is powered (yellow wire, pin 1) with 5.38 VDC (running off the 6VDC heater circuit into a 1M dropping resistor).  the relay doesnt work. adding a ground to pin 16 doesn't do anything.  thoughts? do i need to add a cap with the 1m dropping resistor or something?

[shooter]

ohm pin 1 to 16, should have a coil there, shouldn't be open.
IF you have ohms, put a diode pin 1 anode, pin 16 cathode, retry

[Bieworm]

If my eye is right your diode is put the wrong way around. Look at the stripe on the pcb

[sluckey]

That relay needs 5V @ 100mA to operate. Since you are getting power from a 6V source, you need to drop 1V @ 100mA. That means you need a dropping resistor value of 10 OHMS, NOT 1 MILLION OHMS!

[joesatch]

you may be right but i used the diode this way in other builds without issue. I'll flip it and see. The coil measures 157ohm (powered off)

[joesatch]

using a small dropping resistor isnt gonna reduce the voltage. Can i run this relay at the full 6 volts?

[sluckey]

you may be right but i used the diode this way in other builds without issue. I'll flip it and see. The coil measures 157ohm (powered off)

The band on the relay MUST connect to the positive voltage.

[joesatch]

you may be right but i used the diode this way in other builds without issue. I'll flip it and see. The coil measures 157ohm (powered off)

The band on the relay MUST connect to the positive voltage.

  that's how i have it. These little boards are marked wrong imo

[sluckey]

using a small dropping resistor isnt gonna reduce the voltage. Can i run this relay at the full 6 volts?

6V can only push 6µA through a 1M resistor. That won't do shit.

Sorry, I looked at the wrong part of the datasheet. You have the H1 (high sensitivity) relay. Voltage = 5V, current = 30mA, coil resistance = 166.7Ω. So, you need to drop 1V @ 30mA. Your dropping resistor will be 33Ω.

[joesatch]

success with the 33R resistor. coil is getting 4.93V which is close enough. Thanks Sluckey.

[sluckey]

I tried to present my replies in such a way that you could actually learn something. Hope you did.

[EL34]

I can see that you have the diode reversed from here in NC
Pretty simple to set up the coil

All you need is smooth 5vdc
The + and - hooked up correctly
And the diode put in the correct way.

[joesatch]

is the diode in the right way?  please advise.

[sluckey]

is the diode in the right way?  please advise.

YES

The diode band must connect to the positive voltage. If it were connected wrong you would only have .6V across the coil and that 33Ω resistor would be very hot.

[joesatch]

thanks , yes i see the coil isn't polarity sensitive. I have hooked the positive to the side that is most convenient (closest) to the energy source.

[sluckey]

I can see that you have the diode reversed from here in NC
Pretty simple to set up the coil

Yes it is reversed according to the markings on the board. But he also reversed the power connections. He has the positive voltage connected to the top side of the board. So, this is a case of two wrongs make a right.   

The relay coil is not polarized. It doesn't care which side is positive or negative. But the diode does care and the cathode must connect to the positive voltage.

[sluckey]

thanks , yes i see the coil isn't polarity sensitive. I have hooked the positive to the side that is most convenient (closest) to the energy source.

You do see that the diode symbol etched on the board has the stripe (cathode) on the bottom side in your pic? This means that you should have reversed the position of the diode ***AND*** connected the yellow wire to the bottom side of the board. Then Doug would be happy too. 

[EL34]

is the diode in the right way?  please advise.

Why don't you just reverse the diode and + and - and do it correctly?

[joesatch]

is the diode in the right way?  please advise.

Why don't you just reverse the diode and + and - and do it correctly?

because my + lead is right next to that eyelet

[kagliostro]

I was reading and ....

But to drop from 6V for a 5V relay will not be sufficent to use an in-series diode ?

That will avoid any math calculation, to me

Am I wrong ?

Franco

[acheld]

But to drop from 6V for a 5V relay will not be sufficent to use an in-series diode ?

Yeah, we don't have a schematic, but "normally" a diode is placed in parallel with the relay coil.

Why don't you just reverse the diode and + and - and do it correctly?
because my + lead is right next to that eyelet

You're assuming that a) you will be doing all the servicing of this amp, and b) you will remember how you wired it.

If I service it, I guarantee I will be confused by that diode and the board.   There will be words. 

[sluckey]

But to drop from 6V for a 5V relay will not be sufficent to use an in-series diode ?

Yeah, we don't have a schematic, but "normally" a diode is placed in parallel with the relay coil.

Kagliostro is suggesting to use a diode in series rather than the dropping resistor. A forward biased diode will drop .6V. Close enough. However, the math ain't difficult.   

Still need the de-spiking diode across the coil.

[DummyLoad]

Flip the board over, and everybody's happy! (solder mask down) 

[JPK]

But to drop from 6V for a 5V relay will not be sufficent to use an in-series diode ?

Yeah, we don't have a schematic, but "normally" a diode is placed in parallel with the relay coil.

Kagliostro is suggesting to use a diode in series rather than the dropping resistor. A forward biased diode will drop .6V. Close enough. However, the math ain't difficult.   

Still need the de-spiking diode across the coil.

Yep. A very good thing to have for switching [off] any DC inductive load. I learned this the hard way at a job many years ago.

[acheld]

Kagliostro is suggesting to use a diode in series rather than the dropping resistor. A forward biased diode will drop .6V. Close enough. However, the math ain't difficult.   

Thank you, I misunderstood Franco.