What's this component

[nosamiam]

Hi,

Not strictly on-topic, but the knowledge crosses barriers...

On this page http://www.kerschhofer.net/wurlitzer-replacement-amp/FreeWurli_Schematic.pdf there is a parts list at the bottom. One of the components is "L1" with a value of 2M2. It shows up on the right half of the 1st schematic and toward the bottom of the first layout. Any idea what it is? I've never seen an "L" before.

Also while I'm at it... does anybody have any tips or sources for PCB mount rectangular multiwire connector blocks? With matching male & female parts (2.5mm pitch)? I'm giving myself a headache trying to sort through Mouser's datasheets. If someone knows of an easier way...??

[chilecocula]

It's a 2.2mH coil

[Zben3129]

Well, L generally stands for inductance, and the schematic symbol would fit, but 2m2 seems like an odd value. Henries, the measure of inductance, are generally measured in uH or H, not MH. 2m2 is a common resistor value, and a 2m2 resistor to the collector of that transistor would make more sense than a 2m2 something inductor. Inductors have resistances, but usually ranging form insignificant to 1k

could me a 2.2mH inductor, just with bad notation on the schematic

Zach

[PerroGrande]

I agree -- it is probably a notation error.  Generally, components designated with an "L" indicates an inductor.

My first guess would be 2 mH  -- based on the guess that "2 mH" was erroneously transcribed as 2m2.

Second guess would be 2.2 mH -- although this would be unusual notation. 

I'm not quite sure what this coil is there to do, so I'm not certain how critical the value might be.  It doesn't look like an oscillator, so I'm going to guess that the value is not terribly important.

[snap]

lower case m stands for milli (divided by a thousand)
upper case M stands for mega (multiplied by a million)
be it ohms, amperes, volts, farads, henries, bits, bytes, or flops!

[Zben3129]

lower case m stands for milli (divided by a thousand)
upper case M stands for mega (multiplied by a million)
be it ohms, amperes, volts, farads, henries, bits, bytes, or flops!

This fact actually bothers me, as it is 100% correct, but how manby times have you seen a "2m2 resistor". 2.2 milliohms, anyone?

I don't know why there would be a 2mH inductor there, can't see its function.

2m2 L would be 2.2 milli-inductance? or can L be the same as H? I always thought L = inductance, and H = henries, the measure of inductance? maybe like 180r, r being ohms? Sorry for rambling 


Zach

[PerroGrande]

An inductor measured in Megahenries would be, well, rather substantial!   

If it is a coil, I'd bet it is 2 mH.

[snap]

lower case m stands for milli (divided by a thousand)
upper case M stands for mega (multiplied by a million)
be it ohms, amperes, volts, farads, henries, bits, bytes, or flops!

This fact actually bothers me, as it is 100% correct, but how manby times have you seen a "2m2 resistor". 2.2 milliohms, anyone?

I don't know why there would be a 2mH inductor there, can't see its function.

2m2 L would be 2.2 milli-inductance? or can L be the same as H? I always thought L = inductance, and H = henries, the measure of inductance? maybe like 180r, r being ohms? Sorry for rambling 


Zach

the part is clearly labeled as L1, which states an inductor!
if it were a resistor, it would be named R1!
if it were a capacitor, it would be labeled C1!
if it were a switch, it would be S1!
if it were a doughnut, it would be doughnut1.

furthermore the symbol is different from the resistor, capacitor and switchsymbols,
and definitely doesn`t look like a doughnutsymbol.

the symbol used is the one that often can be found in european schematics and textbooks from the 1960s for:
Inductors!*


another example: a "4µ7" or a "4n7" or a "470p" is often assumed to be a capacitance because of its magnitude
a 6k8 or a 6M8 often automatically is perceived as being a resistance - wrong:
it is just the measure for a dimension or magnitude, but doesn`t give a clue without a symbol or a designator like "C1" or "R1":
with a designator like "L1" as in the wurl-schematic, it clearly only makes sense as "Henry". (2.2mH in this case).


If you would write "4µF7" or "6kohm8" or "2mH2" it would be more obvious indeed! (insert the "omega"-symbol for "ohm").

[George Giblet]

L, C, R are used as schematic designators, or mathematical values in formulas, for inductors, capacitors, resistance respectively

Henries, Farads, Ohms are the *units* used for the part values.

The part is definitely a 2.2mH (milli-henry) inductor.

> I don't know why there would be a 2mH inductor there, can't see its function.

The right hand part of the circuit is a voltage boosting switch-mode power supply.  T1 and T2 form an oscillator, T1 is the main switch, C107 is the output filter.   If you look at the circuit you can see the caps are high voltage so it's generating a high voltage.  The output goes through a 10MEG resistor so that part of the circuit isn't  producing much current.

Checkout,
http://www.dos4ever.com/flyback/flyback.html

[PerroGrande]

The right hand part of the circuit is a voltage boosting switch-mode power supply.  T1 and T2 form an oscillator, T1 is the main switch, C107 is the output filter.   If you look at the circuit you can see the caps are high voltage so it's generating a high voltage.  The output goes through a 10MEG resistor so that part of the circuit isn't  producing much current.

lol...  you're right George -- of course it is!   sheesh... sometimes, I amaze myself, and not in a good way!   

[nosamiam]

I emailed the guy who designed the circuit. Turns out it is an inductor!

If anyone is interested, that circuit is just as the name says. It's a replacement pre-amp and poweramp for any Wurlitzer electric piano. Way, way, WAY simplified from the original.


Mine crapped out on me for the 2nd time and it's kind of a bitch to troubleshoot, given my somewhat limited skills. Last time I tracked it down to a broken lead on a capacitor. This time I just don't want to go through it. Plus I think it's the transformer which would be difficult to source and/or expensive.

So I'm gonna built this an drop it in.