EMI RS124

[DerEber]

Wait, the whole thing if after (or in the middle) of Voltage filtering. So it makes its own thin right?

 

[DaveP]

Thats Right
DaveP

 

[DonnieDarko]

Hey guys,

does anybody happen to have infos on how to build the attenuator for this unit? What switch ( I guess it should have 24 degrees throw) and what resistors to us?

I´m building the Drip Version, which is called 436RS. So far, I got the PCB populated, got most of the pots, all the trannies wired up.

Thanks!

 

[Hank Dussen]

24 degrees throw would make a 15 position switch. I'm not sure if these even exist.
Since the 'original' has 6 positions, you could make an attenuator out of a 2 deck 6 position switch (30 degrees throw) such as a Lorlin.

There are more then 1 type of attenuators. Do you know what type the original had?

 

[DerEber]

Finished my unit and it sounds realy great! I am very happy and want to thank all of you. Without all your contribution
it would not have been possible!
One little Problem is remainig. I get a small pop or bleep every 20 sec. It cancels out somewhat with the Bal-Pot so I assume its some sort of overall feedback. Anyone got some ideas? I have an overvoltage at about 10V wich is not much, but I´ll knock that down and hope for cure. Had same problem with my Federal, so I hope I did not do any unknown fault with my grounding or anything I am not aware of and messing it up again.
best to all,
Stephan

 

[skal1]

? if the current enters the tx primary is 14.5ma ,what is the current coming out of the cathode across the 220 ohm resistor

cheers

skal

 

[DerEber]

Problem solved.
I had some leakage due to very old switch. So the Neon stroke from time to time. Cleaning the switch made it better.
Now one side of the neon is with a 10Meg Ohm to Ground when switched off.  Done!

Really very very nice compressor. Pics coming after developed.

best Stephan

 

[DerEber]

First Pix.... Finished unit still on the roll:

With front

best, Stephan

 

[letterbeacon]

Looks good so far. Is that the Peerless input transformer?

Wait a sec, are you the guy who beat me to the Peerless tx by seconds on ebay the other day?? 

 

[DerEber]

Sorry... no peerless. Its an Malotki.
But works quite good.

 

[lassoharp]

? if the current enters the tx primary is 14.5ma ,what is the current coming out of the cathode across the 220 ohm resistor

cheers

skal

14.5 ma is the typical amount of current the output driver (6cg7) draws in that circuit.  That is the value you get when measuring voltage drop across the cathode resistor (the current flowing through the tube) and it is essentially the same as the current flowing in the tx pri halves.  There are some small losses due mostly to the DCR of the tx pri but you can consider the current measured at the cathode as being the  actual current flowing in the output circuit.  Putting a different 6cg7 in there will likely give slightly, or sometimes greater differences in the voltage and current values.  This is also normal and should be expected.

 

[rjd2rjd2]

Hi all-

So I am approaching "close to done" with my pair of RS 124's that I am building, based off the Altec 436 Drip PCB and the DIY.RACKED faceplate/enclosure. I have a few questions:


1- the "clean/dirty character" switch; it should add/remove R26 and R27 from the circuit via DPDT switch, correct?

2-would the hairball 600ohm T pad attenuator work in place as an output attenuator?

3-how is the stereo link switch, and the anode balance pot, wired?

Thanks so much for the help! (Edited, as i found some of the info i was looking for)

 

[letterbeacon]

I'm slowly gathering all the bits I need to attempt this one. I have a couple of questions though...


How can I work our the current draw for this compressor and is there a Hammond PT that's suitable? I was thinking that the 369AX might be ok, its specs are 250V C.T. @ 115ma, but it's tricky to know without knowing how much current I need.

I've never built a neon circuit before - what sort of neon bulb shall I look for? One that can take 110V, or are there other specs I need to look for.

Thanks for your help in advance.

 

[Rob Flinn]

You can normally work out the current flow through each valve using ohms law on a resistor where you have a voltage reading on the circuit.  say for example you had 1v across a 1K cathode resistor put the figures into ohms law V=IR so I = V/R .  SO you would have 1mA through that valve.  DO this for each half of each valve & add them all together.  You might be able to do this on an anode resistor if the diagram gives you the h.t voltage & you have the anode voltage.  Subtract the anode voltage from the h.t voltage then you know the volt drop across the anode resistor, do the same maths.  When you spec the transformer you probably want maybe 1.5x the current draw you calculate.

 

[letterbeacon]

I managed to get started on my RS124, and finished all the drilling this weekend.

I know it's the most exciting project, but I thought I'd post some pics because everyone likes a bit of DIY porn!

I'm using a Hammond PT, a Sowter OP TX and the original Peerless on the input.

 

[djn111]

Hi,

Looks good, can you be more specific on what you used ?

JJ capacitors by the looks of it ? and what chassis did you use ?

DJN

 

[letterbeacon]

Yes they're JJ caps on the back for the power supply filtering. The big one is 2x 50uf and the smaller one is either a 50uf or a 80uf (I can't check at the moment.

For the OP I'm using the Sowter they make for the Altec 436.

The case is from Holt Broadcast - it's their 150mm deep 2U one.

I'm moving house over the next week or so, but I hope to have a bit of a progress update soon.

 

[r2d2]

A very interesting project 

please there is  a bom list and a doc with some building info , advice , helps  , as well ?
(…Before Behringer "Strike" again…  :'( )
many thanks in advance.
cheers

 

[djn111]

Hi,

In you respond on help etc. This is just a building report, and if you need all that info, are sure you want to build a tube project, point to point with 300V DC in it ?

All the info is in a few RS124 threads, start reading those the parts list is not very big, so easy made from the schematic.

Kind regards

 

[r2d2]

Hi,
In you respond on help etc. This is just a building report, and if you need all that info, are sure you want to build a tube project, point to point with 300V DC in it ?
All the info is in a few RS124 threads, start reading those the parts list is not very big, so easy made from the schematic.
Kind regards

Thanks for post !

i checked fully this 18 pages thread , … many variations (Altec , Emi , VarMu …) and different cool buildings  :
(but no part list or scheme about)
also different schematics scattered here and there on the pages ,

but what schematic is much similar to the actual commercial (authorized) reissue version ?  :

also checked some other thread here as well  ,
i agree about  not much parts are required ,
but not found any info about parts sources ,

anyway i only asked
if a scheme and a parts list also as pencil written draft were  available for share , also by "request" ,
( as for the big part of projects available here )

cheers

ps :
Before China Behringer "strike" again… 
(after "76" ,  "A2A" , EQP1 , who's the "next" ? )