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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 30th Nov 2020, 6:46 pm   #1
DMcMahon
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Default What is this component symbol?

Have been trying to identify the component symbol in the attached photo, looks like a resistor with a line above it, near top of photo, it looks familiar but struggling to recall what it might be.

This is from one version of the schematic for my Uher 95 reel to reel tape recorder, other versions of the Uher 95 schematic do not show it.

The line it is shown in, is the switched +HT (by record switch) to the EM 71 Magic eye recording level valve and also to the Bias oscillator.

From a quick look there appears to be no component in that line in my Uher 95 but just interested to know what the symbol means.

David
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Old 30th Nov 2020, 6:52 pm   #2
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Default Re: What is this component symbol

That's odd: the EM71 shown there does not appear to have a heater!
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Old 30th Nov 2020, 6:55 pm   #3
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Default Re: What is this component symbol

Yes for reasons unknown none of the valve heaters are shown.
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Old 30th Nov 2020, 7:04 pm   #4
Goldie99
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Default Re: What is this component symbol

Reminds me of the symbol used to designate a printed pcb resistor.

Alan
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Old 30th Nov 2020, 7:13 pm   #5
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Default Re: What is this component symbol

Similar to some thyristor symbols?
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Old 30th Nov 2020, 7:43 pm   #6
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Default Re: What is this component symbol?

Looking at the rest of the schematic it looks like an inductor symbol, Philips used that symbol on some of their schematics.

Lawrence.
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Old 30th Nov 2020, 8:12 pm   #7
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Default Re: What is this component symbol?

Because this schematic is stripped of the heaters, the usual valve base pin out/voltages, usual resistor wattages, usual capacitor types and usual playback/record switch full contact details etc, it gives me the impression that it is a more modern schematic that someone has produced stripping out for simplicity.

David
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Old 30th Nov 2020, 11:26 pm   #8
Leon Crampin
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Default Re: What is this component symbol?

At a guess, not being familiar with this machine, your unknown component is a choke - probably a few turns on a piece of ferrite.

Assuming that the EM71 is energised with the bias oscillator on record, a choke here would keep the RF out of the HT supply.

Leon.
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Old 1st Dec 2020, 12:29 am   #9
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Default Re: What is this component symbol?

I'll put my money on an LF choke, too. That solid circle for an indirectly-heated cathode is widespread in Continental practice- just don't go thinking that it means a cold-cathode gas-filled device, a similar convention used in Anglo-American circuits!
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Old 1st Dec 2020, 12:33 am   #10
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Default Re: What is this component symbol?

Thank you to everybody for their inputs.

Seems strange that not shown on original Uher schematics and does not appear to be fitted in my machine.

I wonder it was something extra that the person who did the schematic had added maybe as Leon has suggested for RF filtering.

David
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Old 1st Dec 2020, 4:17 am   #11
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Default Re: What is this component symbol?

G'day everyone.
Definitely a choke. Value not known but that is what it is.
I have experience with Ericsson telephone equipment and their wire wound chokes and relay coils etc. are represented like this.
The single line means it has a core.
I will back what the other posters have stated. Probably a low frequency choke.
Cheers all.
Robert.
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Old 1st Dec 2020, 9:05 pm   #12
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Default Re: What is this component symbol?

Could also be a power resistor? Probably wrong but I seem to think somehow. Odd, no value.
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Old 1st Dec 2020, 9:48 pm   #13
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Default Re: What is this component symbol?

In dad's 1933 copy of Scott-Taggart's book "Manual of Modern Radio", the choke symbol with three horizontal lines running axially through the turns represents an iron- cored (low frequency) choke. For RF chokes the conventional curly winding symbol is used with no through lines. So, as others have suggested, it probably means a cored inductor.
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Old 2nd Dec 2020, 11:34 am   #14
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Default Re: What is this component symbol?

None of the components on this particular schematic have the usual designations, eg. R1 , C2, L3 etc but they all have their values where applicable e.g. 10kOhms, 100nF etc but nothing for the mystery component (choke/inductor).

David
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Old 2nd Dec 2020, 3:34 pm   #15
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Default Re: What is this component symbol?

Ferrite bead on a wire?
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Old 16th Dec 2020, 12:18 am   #16
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Default Re: What is this component symbol?

No heaters in this EZ80 or any of the other valves either - somebody has taken them all out and lined them up at the bottom of the drawing.....
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Old 16th Dec 2020, 4:44 pm   #17
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Default Re: What is this component symbol?

That symbol - but without the accompanying single line - is used to signify a "Moving Iron" loudspeaker in some 1930s German circuits.

See the diagram here: https://www.radiomuseum.org/tubes/tube_vel11.html
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Old 17th Dec 2020, 4:28 pm   #18
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Default Re: What is this component symbol?

Out of interest how do you know the component with that zigzag line (resistor type symbol) in the linked drawing is a Moving Iron loudspeaker ?

David
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Old 17th Dec 2020, 5:02 pm   #19
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Default Re: What is this component symbol?

It can't be much else unless part of the schematic has been left out.

Lawrence.
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Old 17th Dec 2020, 5:45 pm   #20
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Default Re: What is this component symbol?

Talking of which:

http://www.oldradio.de/wiki/index.ph..._Schaltung.png

Lawrence.
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