If you want to confirm the ratio, just wind on 10 turns of small Ga wire and obtain the T/V by volt meter measurement.
Max.

 

You should not need any filtering for DC relays, or even regulation if the voltage is withing reason of the relay rated V.
Max.

The application will certainly need filtering for those DC relays, otherwise they will buzz and possibly burn the contacts from the buzz. I have been down that road, Max. A rectified supply delivering 18 amps will have LOTS of ripple to make relays buzz.

 

After hearing such tales of possible relay 'buzz' when fed from raw DC with 120hz ripple I carried out a lengthy emperical test of various DC relays of different physical size and makes, including an automotive relay, using a Variac and a unfiltered DC bridge.
I raised the DC gradually through the hysterisis points both using increasing the DC up to the pick-up point and also reducing the DC until drop out occured.
At no point did any of the relays 'buzz' or 'chatter' during the test.
Therefore the DC not only had 100% ripple but was tested from 0v to full operating voltage.
Also I have used them this way in applications and installations without seeing any ill effect due to chatter.
Max.

 

I have been down that road

Are you sure you aren't talking about DC voltages operated from AC?

 

After hearing such tales of possible relay 'buzz' when fed from raw DC with 120hz ripple I carried out a lengthy emperical test of various DC relays of different physical size and makes, including an automotive relay, using a Variac and a unfiltered DC bridge.
I raised the DC gradually through the hysterisis points both using increasing the DC up to the pick-up point and also reducing the DC until drop out occured.
At no point did any of the relays 'buzz' or 'chatter' during the test.
Therefore the DC not only had 100% ripple but was tested from 0v to full operating voltage.
Also I have used them this way in applications and installations without seeing any ill effect due to chatter.
Max.

My results were different. Probably because the relays that I was using were different from the ones that you used. AND also, my system was usin half-wave rectified power.

 

Also to add, there are many thousands of large DC brakes and clutches, as well as DC solenoids used all over the world on such as overhead Gantry cranes and hoists among other applications, all using simple bridge output.
The addition of a BEMF diode also aids in holding the armature in during ripple, in some cases this delays the switch off in large inductors, and can be slightly detrimental.
Max.

 

AND also, my system was usin half-wave rectified power.

Well that certainly explains the difference.
A half-wave rectified signal is a series of 50% duty-cycle pulses.
I would expect that to cause a buzz in any relay, AC or DC.

 

Well that certainly explains the difference.
A half-wave rectified signal is a series of 50% duty-cycle pulses.
I would expect that to cause a buzz in any relay, AC or DC.

Many AC relays include what is called a "shading coil", which usually is a single turn of copper around a portion of a pole. The DC relays lack such a coil, which is one way to tell an AC relay from a DC relay.

 

Many AC relays include what is called a "shading coil", which usually is a single turn of copper around a portion of a pole. The DC relays lack such a coil, which is one way to tell an AC relay from a DC relay.

Yes.
But I would still expect an AC relay to buzz when powered from a half-wave rectified source.

 

Yes.
But I would still expect an AC relay to buzz when powered from a half-wave rectified source.

The last project like that was quite a while back and I have no recollection of what I may have done to prevent buzzing. So I am not in a position to say one way or the other.
That project used a sensitive grid thyratron tube as a proximity detector. Sort of like a capacity relay device, except passive, no oscillator to detect. It worked by sensing an increase in the ambient AC field that is all around us. The tube was a type 2050, if you are interested.

 

The coil resistance of the AC version relay is Much lower than its DC counterpart.
Usually precludes any usage on DC.
Max.

 

Everything finally came together with this project and I'm really happy with the outcome.

I just wanted to say thanks to everyone for sharing their expertise. It is much appreciated and I wouldn't have gotten off the ground otherwise!

 

I am glad that it works well for you, I have wondered about those stair-lift devices and how well they would perform. AND thanks for posting a copy of the circuit.
I looked at the circuit drawing and while I could understand it I would not ever use the symbols for relays that were used, because they do not show the coil explicitly.