Regurgitator kit Build Thread

[Joe Malone]

Alright, that's perfect. One last question, and I stop bothering you... What would you recommend for powering those and adding a on/off LED ? I'm not very keen on putting a power tx in side the rack because of the un balanced wires in it. Do you have a clean way to make this externally, via say a SMPS, and then get +-18v rails internally ?

We use our tiny 48v 15w internal SMPS turned down to 36v and fit 18v zeners to the regurgitator pcb to make +/-18v. A 6.8k resistor in series with a cheap led between _18v and +18v works fine.

[bendi]

Hi Interesting problem with the Regurgitator. Adjusting the potentiometer for a Vout of 0.775 mV I find that the output voltage as viewed on the CRO increases in jerky fashion. That is increases, decreases, increases and so on as the trim pot is adjusted in a linear fashion. The power rails are fine: +/- 17 V

The other Regurgitator cards that I have, adjust smoothly. The only hiccup that I have had in the past, is that I may have stressed some components due to a massive short to chassis with one of the power supply rails a few weeks back which took out the AC/DC 3 Rail power supply.
All my Regurgitator cards have worked in the first instance, including this one which now, is the black sheep.

The 5k trim potentiometer was replaced and a few suspect solder joints cleaned and resoldered. The opamp is NE5532AP, swapped and appears to be okay.
Any ideas please, to fix this issue would be appreciated greatly. Regards Mark (Bendi)

[dane999]

We use our tiny 48v 15w internal SMPS turned down to 36v and fit 18v zeners to the regurgitator pcb to make +/-18v. A 6.8k resistor in series with a cheap led between _18v and +18v works fine.

Would this be robust enough for 14 modules ? Do you have an idea of the current draw for 14dB of gain, or which fuse would you use for this ?

[Joe Malone]

We use our tiny 48v 15w internal SMPS turned down to 36v and fit 18v zeners to the regurgitator pcb to make +/-18v. A 6.8k resistor in series with a cheap led between _18v and +18v works fine.

Would this be robust enough for 14 modules ? Do you have an idea of the current draw for 14dB of gain, or which fuse would you use for this ?

With NE5532A current is about 16mA per regurgitator plus current into 18 zeners of about 5mA each regurgitator.

So work on about 21mA each regurg so about 300mA total so shoudl work fine.

I would turn down the power supply to about 35v and measure across a 10R on one regurg and turn up the power supply until you get 0.2v across the 10R.

[Joe Malone]

Hi Interesting problem with the Regurgitator. Adjusting the potentiometer for a Vout of 0.775 mV I find that the output voltage as viewed on the CRO increases in jerky fashion. That is increases, decreases, increases and so on as the trim pot is adjusted in a linear fashion. The power rails are fine: +/- 17 V

The other Regurgitator cards that I have, adjust smoothly. The only hiccup that I have had in the past, is that I may have stressed some components due to a massive short to chassis with one of the power supply rails a few weeks back which took out the AC/DC 3 Rail power supply.
All my Regurgitator cards have worked in the first instance, including this one which now, is the black sheep.

The 5k trim potentiometer was replaced and a few suspect solder joints cleaned and resoldered. The opamp is NE5532AP, swapped and appears to be okay.
Any ideas please, to fix this issue would be appreciated greatly. Regards Mark (Bendi)

Sorry Mark I had missed this post somehow

No idea on this one as we have never had a problem with the regurg. Best to email me some photos of the top and bottom of the offending PCB so I can see the setup which may give me a clue. You have checked the two 10R resistors are still 10R?

[dane999]

Hi Joe,

I've built one kit to test it. It balances fine, works fine, but it seems that I can't get those 18dB of gain (I need 14). The plan here is to raise the -10dBu direct output of a Studer 169 to +4dBu.
I inject a -10dBu sine (0,244Vac on the input between 0V and 2), and with the trim pot turned all the way up, I get 0,903Vac on the output (between 2 and 3), and the input seems to clip very quickly, around 0,48Vac.
I'm wondering if it's the measurements or the build that are wrong... Do you have any clue, or test points to verify my build ?

[Joe Malone]

Hi Joe,

I've built one kit to test it. It balances fine, works fine, but it seems that I can't get those 18dB of gain (I need 14). The plan here is to raise the -10dBu direct output of a Studer 169 to +4dBu.
I inject a -10dBu sine (0,244Vac on the input between 0V and 2), and with the trim pot turned all the way up, I get 0,903Vac on the output (between 2 and 3), and the input seems to clip very quickly, around 0,48Vac.
I'm wondering if it's the measurements or the build that are wrong... Do you have any clue, or test points to verify my build ?

Best to send me some photos of the pcb top and bottom and the wiring etc and power setup so I can check it over.

what dc voltages do you have at all opamp pins measured to 0v ?

[dane999]

My voltages are :
pin 1 : 18mV
pin 2 : 0V
pin 3 : 0V
pin 4 : -14,9V
pin 5 : 0V
pin 6 : 0V
pin 7 : -18mV
pin 8 : 14,9V

Here are some pictures of the PCB. The connections are temporary for testing purposes.
Thanks for your help !

[Joe Malone]

My voltages are :
pin 1 : 18mV
pin 2 : 0V
pin 3 : 0V
pin 4 : -14,9V
pin 5 : 0V
pin 6 : 0V
pin 7 : -18mV
pin 8 : 14,9V

Here are some pictures of the PCB. The connections are temporary for testing purposes.
Thanks for your help !

The 15k resistors do not seem to be 15k? Have you measured them? They look like 120R?

[dane999]

HI,
I did measure them when building, and unsoldered one today, and also measured the ones in the other kits (looking the same), all 15k !
Are the 18dB of gain available only when connecting a balances input ? My main concern is the fast clipping of the device, around -8dBu when pushed to max gain...

[dane999]

Well, I did build another one, very carefully, and the problem is the same. I swapped the 5532 with one I had lying around, and the circuit behaves exactly the same. I'm starting to think that my measurement method is all wrong, and that the circuit is working...

[dane999]

Well, I redid every solder joint on the one that was problematic, built the 13 other ones, and the unit works perfect. Thanks for your support Joe, and sorry for the bothering.

[Joe Malone]

[quote="dane999"]Well, I redid every solder joint on the one that was problematic, built the 13 other ones, and the unit works perfect. Thanks for your support Joe, and sorry for the bothering.

No bother at all. Great to hear you got it all working Beautifully neat build and layout.

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[Yves]

Hello Joe,
I need an advice concerning powering the Regurgitator.
I would use it to balancing the input of an build in amplifier (monitor speaker) with the power supply of the amp (+/- 30V).
- Is it ok if I add two 18v zener diodes (BZX85C18) or you advise less zener voltage ?
- Need I to place two resistors before the Regurgitator power input ? or just change the value of R14 and R15 ?
Thanks

[Joe Malone]

Hello Joe,
I need an advice concerning powering the Regurgitator.
I would use it to balancing the input of an build in amplifier (monitor speaker) with the power supply of the amp (+/- 30V).
- Is it ok if I add two 18v zener diodes (BZX85C18) or you advise less zener voltage ?
- Need I to place two resistors before the Regurgitator power input ? or just change the value of R14 and R15 ?
Thanks

Yes fit the 2 x 18v zeners. Good idea to mount the zeners 5mm in the air for better cooling.

You could change the 2 x 10R on the pcb but these resistors will need to be made larger 1W versions so will not fit well there.

So running them in series off pcb is a good idea. Or use 2 x 0.6w metal film of half the value in series where each 10R was in a triangle shape.

If it is one regurgitator kit with NE5532A add 330R 1W resistors in series with the +/-V of regurg and +/-30v of amp. Each resistor will put out 0.5W of heat.

If it is two regurgitator kits with NE5532A add 150R 2W or 5W resistors in series with the +/-V of regurg and +/-30v of amp. Each resistor will put out 1W of heat. Only fit 18v zeners to one regurgitator pcb if pcb still joined. If PCB separate just run them with separate 330R resistor and zeners as above.