Cossor 464 bluetooth

[Gabe001]

Very smart. I'll need to experiment a bit. Will let your you know how things pan out

[Gabe001]

Originally Posted by wd40addict

Here's a different module I've fitted into my Blaupunkt Santos. The Santos has a pick-up input so switching or resistor removal not required. The challenge here is that the radio is a live chassis type. The heaters are all run at 6v3 with one side connected to chassis. I modified an eBay 5v regulator kit to half wave rectification and used it to feed the KRC68. See attached pictures.

Module is mounted inside set for safety as mains reversal could make the pickup sockets live!

I'm going to give it a go with half wave rectification using a schottky diode, a large capacitor and a 5v voltage regulator first. It worked for others here, so fingers crossed. I didn't know you could get full wave rectifier bridges ready made, but if I get my power setup right it should work for any set.

Thanks for your help

Gabriel

[Gabe001]

Hi WD,

I gave this a go on an ultra twin live chassis, as an experiment.

Powering the module wasn't a problem, although I used an encapsulated Stepdown transformer (240-9v) and half wave rectification directly from the switch. This is because the current draw of the filaments is only 40mA, so taking 20mA from there would have stressed the set

In any case powering the module and half wave rectification of the 9v AC worked fine.

I managed to feed the Bluetooth signal to volume control, overriding the radio and it worked well, provided you're on a quiet section of the tuning scale. Very clean signal no noise, good volume with 2 x 330 ohm
resistors. Inputs not used (yet)

However when the Bluetooth was powered but waiting to pair I got terrible interference. Once I pair, signal is clean. I haven't used the capacitor on the output yet and haven't put the 3m resistor on yet. Also am using the indicator led so I know that the module is powered and what the module is doing

Can I ask you what value capacitor did you use on your output and does the 3m resistor go from one of the inputs to ground (based on your picture)? Also can I use the indicator led or should I remove it?

Thanks
Gabriel

[wd40addict]

I used 1uf because I had it to hand. The 3M resistor is between one of the inputs and ground. It could equally go on the BT output before the 1uf cap. When Bluetooth is not connected the resistor puts some bias on the capacitor so it's not just being biased by the ESD diodes within the analogue switch. I assume you have removed the 100k resistors?

The current drawn by the module seems quite spiky in nature and a nice low ESR cap directly on the 5v input spins smooths this out (red cap in photo).

I would remove the LED, it's just something else to draw current and maybe being fed from a noisy supply.

I am not familiar with the ultra is it Trader 1100? If so you don't need the 1uf & 3M because C16 is blocking DC from the volume control.

[Gabe001]

Thanks for your reply. It's an ultra twin r766.

Yes I used the smoothing cap after the regulator. I wonder if the blinking led was causing some issues.
The 100k resistors were removed
Regarding the resistor and cap, relevant section of trader sheet attached. I think DC is blocked at volume contol but feel free to double check.

Thanks again. I'll give it another go this weekend and see. Waiting on some valves.

Gabriel

[wd40addict]

C13 is blocking DC from the volume control so need for 1uf and 3M.

I note your mention of 2*330R. You don't need any series resistors just connect L to R on the module and wire combined output to volume control using screened cable. Connect your power supply direct to module, do not run 0V down the lead carrying the audio.

I ran some IMD tests on the module and connecting L to R only gave increased distortion if the test signal was panned 100% left or right.

[Gabe001]

Ok, I'll report back in a few days once I've given this a go. Thanks again

[Gabe001]

WD, I can confirm that it was the LED that was causing noise. Great with the indicator LED removed

Powering the module with half wave rectification (schottky diode + 2200uf+ 5v voltage regulator) worked well first time round.

Thanks for your help
Gabriel

[wd40addict]

Excellent news!

I never fitted the diode as it would be hidden and I wanted to minimise current draw.