Simple Magic Eye Circuit Wanted

[poynton]

Hi.



I have several magic eyes but I like the look of the EM71.

Does anyone have a simple circuit to drive and power on of these??


Andy

 

[jeffdavison]

http://www.akh.se/tubes/htm/em71.htm

 

[fsjonsey]

I have a little magnavox amp with an unused tube socket that i'd like to do something similar with. I have a bunch of NOS EM84's laying unused.

 

[poynton]

http://www.akh.se/tubes/htm/em71.htm

Hi
Thanks - that will probably do the job !

What resistor / drive arrangement will be required on the input ?

I assume a capacitor will be required so it's AC not DC ?

Andy

 

[Jeb-D.]

If using it as a level indicator to detect a signal that contains no DC. You will have to rectify the signal to produce a negative voltage. Then use a cap to filter it to -DC. So a diode and a cap or a bridge rectifier and a cap. And you will probably want to put a bleeder across the cap so it doesn't just hold the lowest value for ever.

If detecting a signal that also contains a positive DC. You must first use a coupling cap to block the positive DC before doing the process mentioned above.


If your using it to detect bias I'll have to see the circuit your adapting it to.

 

[poynton]

Thanks

I just want to put a level indicator on the front of an amp.


Andy

 

[Jeb-D.]

From that spec sheet it looks like the range is 0-20V. So you will have to tap it off a pretty strong signal. And you may have to make a voltage divider to give you good range on the display.

 

[Tubes4e4]

The attached circuit is an excerpt from one of my projects. EM71 has an interesting non-linear, degressive characteristic somewhat suitable for output level (power) "metering", showing movements at low levels already, while not running into full reading too fast.

Tom

P.S.: The C3 value as shown is vast overkill; depending on B+ quality this cap even can be left out altogether.

 

[thecobraman]

well hi all,,,mark this side from bradford
i have..a video on my youtube for EM71 Magic eye IN STEREO
or the em84 tube look for thecobraman EM71 Magic eye IN STEREO
just Let me know if you need more info mark

 

[frankln]

The attached circuit is an excerpt from one of my projects. EM71 has an interesting non-linear, degressive characteristic somewhat suitable for output level (power) "metering", showing movements at low levels already, while not running into full reading too fast.

Tom

P.S.: The C3 value as shown is vast overkill; depending on B+ quality this cap even can be left out altogether.

Hi Tom i'm building this project.

An externally hosted image should be here but it was not working when we last tested it.

Some suggestion for wiring magic-eye EM71?

thanks
Francesco

if the image do not open please go to this link:
Super triode connection Ver.1 6BM8 single ended. stereo power amplifier 2nd model