Stylus arm switch.........

[Spoon]

Hi people.
I'm after a stylus arm switch.
The brother-in-law is doing a little project where when the record is playing a few LED's light up. Now the circuit is simple but we can't find a suitable switch. He doesn't want a prox switch as he doesn't want it powered all the time.
The switch will have to be activated with very little effort. I haven't seen the player what hes thinking of doing this too but there must be a micro switch out there that activated with very little effort.
Any idea's?

 

[Squid]

33rpm or 78rpm?

 

[Leesparkykent]

Sorted

 

[Spoon]

Personally, if it was going to be a permanent fixture on a particular turntable, I'd be looking to take a feed from the motor drive.

Apparently the turntable is a Quartz controlled system and taping into it will change the turntable speed.

 

[SparkyChick]

Apparently the turntable is a Quartz controlled system and taping into it will change the turntable speed.

Ok, so there is some form of electronic drive with a feedback mechanism... this will require some control signals, like a run signal. Likely to be low voltage, you could tap that. Using a (off the top), NPN transistor... collector to say 5v, emitter to a relay (to provide the power switching - not forgetting a flyback protection diode) and base to the motor run signal, via a resistor (to limit the current).

That's the route I'd go.

 

[sparkdog]

You could probably use an optocouple, it wouldn't need any force to operate.

 

[SparkyChick]

Sorted

Thanks

 

[Squid]

What turntable is it and whats the rest of the setup, is he an analyst?

 

[Spoon]

I have just found out it's a Hitachi HT-354 or a HT-356.
We haven't discussed this a lot. I will find out more.

 

[UKMeterman]

bit of white tape on the side of the turntable high pass filter and some photo detectors, once the pulse rate is over 33 rpm launch the lights...

 

[Lucien Nunes]

As far as I can see from the manual, there is a microswitch that cuts the mains feed to the transformer when the arm is on its rest. You could connect a 230V AC relay coil across the ends of the transformer primary (split for 120/240V selection), or a 24V AC one across the ends of the secondary (CT-E, produces a split DC rail of +/- 14 or 16V depending on model), or a 24V DC one with a bit of extra resistance between the two DC rails. There is no other power switching within the drive electronics.

If for any reason you add a your own microswitch, it must work the same way i.e. it is operated when the arm is at rest, but totally disengaged from the arm when playing. Even the tiniest force will disrupt the tracking.

 

[Spoon]

As far as I can see from the manual, there is a microswitch that cuts the mains feed to the transformer when the arm is on its rest. You could connect a 230V AC relay coil across the ends of the transformer primary (split for 120/240V selection), or a 24V AC one across the ends of the secondary (CT-E, produces a split DC rail of +/- 14 or 16V depending on model), or a 24V DC one with a bit of extra resistance between the two DC rails. There is no other power switching within the drive electronics.

If for any reason you add a your own microswitch, it must work the same way i.e. it is operated when the arm is at rest, but totally disengaged from the arm when playing. Even the tiniest force will disrupt the tracking.

Ta mate. I'll let him know.. It's up to him which way he wants to do this. I'll be seeing him in a couple of days.