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Messages - tpb03

#1
Any update on the progress. I see in the news that the pcbs have arrived   :dbtu:
#2
Hi Brian,

Start with a Ruby amp, it's really simple based upon the LM386 IC. It's only 1/2 to 1W but will power a 4x12" loud enough to annoy the neighbours.

A good source of information is Beavis Audio - lots of basic info and breadboard layouts.

Tim
#3
An update - I finally finished this project. I ended up buying a bunch of cheap boards from EBay and after testing them all decided to abandon the TDA2050 board and use a 2x10W class D PAM8610 similar to this one (https://bit.ly/2GMHbf4). It sounds a lot better with less noise than the TDA.

The power amp is running at 12V and I use an LM2596 based step down converter design for model aircraft to provide a 9V for a fetzer value circuit which is the preamp. I also have an output for the second channel so I can run another speaker for a total of 20W. Overall sounds good with tone that is faithful to the original fender 5f1. The speaker is an 8" from a Park G10.
Some Pics attached (or via links) - including a guts shot
https://imgur.com/a/FqtBkds
https://imgur.com/a/0dFU46P
https://imgur.com/a/em9Ofyl

#4
Amplifier Discussion / Re: EBay TDA2050 boards
October 11, 2017, 07:42:58 PM
Just a quick update - I have received the board and set that up and played audio via my iPhone through it. So I can conform that it is working in order.

I have layed out the schematic I posted above on my breadboard running at 20V. When I measure the drain voltage between R4 and the drain I am not seeing any voltage drop, it is measuring at 20V still - shouldn't I expect this to be half the supply voltage so 10V?

Am I measuring for the bias voltage in the right place? Do I need to run a signal (ie guitar) through the circuit to bias the JFET?
#5
Just a quick question re resistors to set Vd & Vs for voltage biasing in the schematic. If I want to run at 12V or 19V (I have these power supplies), should I just use the calculators on the ROG Fetzer Valve revisited page after working out the Vp and Idss for my MPF102? The values in the schematic are twice that of the average values on the ROG page.

#6
Amplifier Discussion / Re: EBay TDA2050 boards
September 17, 2017, 08:22:52 PM
Thanks J M.

I will treat it as per the datasheet single supply. I also have a TDA2030 board that is claimed 15W 6-12V single supply. As I have the TDA2030 board already, I will test it at 12V and then higher just playing music from my phone.

I have been searching for a preamp and found this schematic on the forum (post https://www.ssguitar.com/index.php?topic=1778.15).

It is Runoffgroove's Fetzer Valve with a buffer. This should give me a good approximation of the Champ tone going into the power amp board. Its also setup for 18V, although I did have a look through my laptop supply collection and the nearest is 19V. I'll test them all with my multi-meter to work out true voltages as from experience laptop supplies and wall-worts can be +/- 2V either way.

I would like to modify the preamp for two inputs like the 5F1. I'll report back when I proto this, but I think I will need to change the 4.7K input resister to 2 resisters running in parallel like the champ input. I can then solder the 1 Meg resister from active to ground on the input jack rather than on the board.



As for speakers, I have an 8" 8 Ohm guitar speaker from an old Park G10.

I'll report back here to share my experience as I am bound to need to help along the way!

Tim
#7
Amplifier Discussion / EBay TDA2050 boards
September 12, 2017, 08:52:34 PM
A few years ago I started to make a small combo amp for practicing in my bedroom. Due to starting a family I ran out of time and abandoned the project, but not before building a nice pine cab based upon the Fender 5F1 combo.

I now want to complete the project as a 5W SS Champ style amp. I have ordered one of these cheap TDA2050 boards form ebay http://www.ebay.com.au/itm/DC-12-24V-5W-120W-TDA2050-Mono-Channel-Audio-Power-Amplifier-Board-Module-kit-/142443279688 which from the TDA2050 datasheet will deliver about 5W into an 8 Ohm speaker  at 18V single supply (I have some old 18V 4A laptop power supplies). I don't really trust the claims of 12-24V 5W- 120W, but happy to be shown wrong!

Could this project be as simple as (input -> Fetzer valve -> TDA board -> speaker) or do I need to put a buffer in somewhere? Also when running a fetzer vale at 18V, do I bias the transistor at 9V? (I obviously need to do some homework).

Does anyone have any experience using these prefab boards?

Tim
#8
Great, thanks Meffico and Pyromaniac.

I'll have a go at building and report back. I might try both perf and vero layouts.

Tim
#9
Sorry to drag up this old thread. Has anyone got a copy of the original layout? The file in the original post is not displaying for me.

Cheers

Tim
#10
Amplifier Discussion / Re: TDA7850?
December 17, 2012, 09:43:24 PM
Actually,
how does the TDA1562 chip fair for Guitar. Seems like a pretty good candidate for an amp as well.

Tim
#11
Amplifier Discussion / TDA7850?
December 17, 2012, 05:46:49 PM
I have seen some kits on ebay which use a TDA7850 chip which claims 4 x 50W from a 12v supply. Is it possible to use these kits in a guitar amp? Can you bridge the 4 channels into 1 output or just use one of the channels for a 50W amp?

Tim