Hello, first post 

I've built a musikding.de rangemaster germanium treble booster clone. Ít worked fine for a few months but now its started clicking. Ive tested it alone (no cahin) and with batt and power supply separately, to no avail. It still clicks.

The clicks are not extremely loud, but are clearly audible. It is one click about every two seconds but this varies. The clicks are not regular.
Any suggestions appreciated.
thanks

Hi & Welcome..

Are we taking about this project..??

If yes, check for leaky C4..
(just disconnect one of its legs..)

P.S.
A leaky C5 could make an interesting tremolo effect..

Turn off or move away from all Wi-Fi devices. Maybe BlueTooth too. Maybe cellphones generally.

Quote from: PRR on February 09, 2025, 02:30:24 PMTurn off or move away from all Wi-Fi devices. Maybe BlueTooth too. Maybe cellphones generally.

Haha, nowadays that means leave your home and walk into the desert!

Quote from: Clint Eastwood on February 09, 2025, 03:16:26 PMnowadays that means leave your home and walk into the desert!

Quite right but, unfortunately, bass booster is what you need in a desert..

Quote from: PRR on February 09, 2025, 02:30:24 PMAre we taking about this project..??
YES

If yes, check for leaky C4..
(just disconnect one of its legs..) what effect will disconnecting the cap have on the circuit? will it still work at all?
thanks!

Quote from: antonis on February 09, 2025, 12:41:49 PMif C4 (100uF) is leaky, I have 2 choices from bits I have in stock:
1. replace it with a 100uF tantalum cap
2. connect two normal 470 uF electrolytic caps in parallel

presumably tantalum would be best option?

C4 is a filter capacitor for the power supply rail (9v+) to avoid instabilities that may cause oscillations, and if it is faulty, it could induce noise in the circuit.

Paralleling capacitors sums their value (it's the inverse of how it works for resistors), so 2x 470uF in parallel = 940uF.
For your C4, there's no real need to be precise, so you can just use any value that's above the schematic stipulated 100uF.

Having said that, just a side note: an unspoken but common rule of thumb we use in the hobby for choosing components like capacitors in our projects, is to always get them rated for around 2x the maximum voltage in the circuit (so for 9v, at least 16v rated components). This ensures the components will never reach their rated limits which means they're less likely to fail or cause issues.

Quote from: blackcorvo on February 10, 2025, 07:37:06 AMParalleling capacitors sums their value (it's the inverse of how it works for resistors), so 2x 470uF in parallel = 940uF. yes I actually knew that but im getting old   somehow I confused 470 with 47
For your C4, there's no real need to be precise, so you can just use any value that's above the schematic stipulated 100uF.since I have nothing else to hand, presumably the 100uF tant. would work just as well as a normal cap, even though its only for power filtering?

Having said that, just a side note: an unspoken but common rule of thumb we use in the hobby for choosing components like capacitors in our projects, is to always get them rated for around 2x the maximum voltage in the circuit (so for 9v, at least 16v rated components). This ensures the components will never reach their rated limits which means they're less likely to fail or cause issues. thanks, Ill keep that in mind!

I'm trying to read quoted quotes, but..

So, before replacing anything, did you try to diconnect that cap..??

Germanium transistor leakage may depend on base voltage, so as the input capacitor C2 charges toward the collector, the leakage may suddenly stop and discharge.  Whenever I see a problem with a germanium transistor circuit, I tend to try another transistor before anything else.  I remember transistor radios where a second audio amp stage had its base connected via an electrolytic capacitor to the collector of the previous stage.  There were no bias resistors on the base - transistor and electrolytic leakage were supposed to bias the transistor.  These only worked over a limited temperature range.

And that is something else to try - stick the unit in the refrigerator and see if the rate of the ticking sound changes.  If it does, chances are the problem is the transistor.

Aah,
just discovered c4 and c5 have swapped values... wonder who did that
Ill put em in theor correct places and see what happens

Quote from: amptramp on February 10, 2025, 09:46:48 AMGermanium transistor leakage may depend on base voltage, so as the input capacitor C2 charges toward the collector, the leakage may suddenly stop and discharge.  Whenever I see a problem with a germanium transistor circuit, I tend to try another transistor before anything else.  I remember transistor radios where a second audio amp stage had its base connected via an electrolytic capacitor to the collector of the previous stage.  There were no bias resistors on the base - transistor and electrolytic leakage were supposed to bias the transistor.  These only worked over a limited temperature range.

And that is something else to try - stick the unit in the refrigerator and see if the rate of the ticking sound changes.  If it does, chances are the problem is the transistor.

why would making it colder change the rate?

Quote from: antonis on February 10, 2025, 09:29:52 AMI'm trying to read quoted quotes

They don't quote the messages they link, but something further in the past.

Quote from: scooby on February 10, 2025, 09:52:37 AMwhy would making it colder change the rate?

Germanium transistors are very sensitive to temperature, and if the issue is related to current leakage on the transistor, cooling it down will affect the rate of the clicking because it will change the current leakage. If it doesn't change, the issue is somewhere else.

Quote from: blackcorvo on February 10, 2025, 02:05:10 PM

Quote from: scooby on February 10, 2025, 09:52:37 AMwhy would making it colder change the rate?

Germanium transistors are very sensitive to temperature, and if the issue is related to current leakage on the transistor, cooling it down will affect the rate of the clicking because it will change the current leakage. If it doesn't change, the issue is somewhere else.

Exactly.  Leakage is such that every 10°C rise in temperature doubles the leakage current.  So a 20°C drop in temperature due to being in the refrigerator would cause the leakage to be a quarter of what it was at room temperature.  Germanium was a good way to make a transistor using simple processing.  If a germanium device vaguely looks and smells like a transistor, it will work.  But leakage is a major problem with germanium as it has a thousand times the leakage of silicon and it can't be passivated.

Ok. So putting it in the freezer for a day doesn't affect the clicking speed.  Since c4 and c5 were originally installed in swapped positions, (now corrected), but the clicking remains, presumably c4 is not the problem?

Did you try with C4 disconnected..??

The rationale behind this is related with indicator LED curent draw and power supply health..

disconnected C4 leg and now its just constant static

Quote from: scooby on February 18, 2025, 07:00:00 AMdisconnected C4 leg and now its just constant static

Sorry but I don't get you..

Do you mean it's clicking at a constant rate..??