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OLD THREAD DAC End by Andrea Ciuffoli

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#824
Set times for Relay

my relay wont engaged, it chatters and chatters but wont engage. Takes about a minute then it starts chattering.

No problem! Times of relay. you relay is very good! The Relay 5 or 6V is ok!

Set tim for Relay use change C 12 in the Board I/v stage:
C12 = 220uf = 1 min relay start
C12= 100uf = 45 s relay start
C12 = 47uF= 30 s relay start
I think you use C12 = 47uf.
thank you!
 
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#829
Edit

This is not bizarre. I think i worked out whats going on.

I was messing with the 2r2's, trying different values becuase of excessive heat and i was close to dropping out of regulation with the 1085 IC.

In doing this i then needed to alter the the R11 again (which i hadnt done).

So with R11 at 700ohms, and R8 and R9 the regulation is stable and i am not getting chattering.

I should have been more methodical.
 
#830
adamus said:
Edit

This is not bizarre. I think i worked out whats going on.

I was messing with the 2r2's, trying different values becuase of excessive heat and i was close to dropping out of regulation with the 1085 IC.

In doing this i then needed to alter the the R11 again (which i hadnt done).

So with R11 at 700ohms, and R8 and R9 the regulation is stable and i am not getting chattering.

I should have been more methodical.
Click to expand...


Adamus don't rush to connect the boards to the two power supply before you tested them with load.
Step by step.

First you should test the HV fully loaded. Connect 2.2R+2.2R+2.2R+2.7R 5W each series on 270V. You must check with oscilloscope if the regulator is doing its job.
At the same time connect 2 10R 10W parallel to heater DC and check with oscilloscope you must not have ripple. You don't know if you don't check with oscilloscope.
You must load both heater and HV to make sure the transformer's internal regulation can maintain the sufficient voltage for both rails.
Your relay could chatter because ripple on 6.3V or relay too high voltage.
Relay must be 5V. It can work on 125% the nominal voltage so it forgives you.

After you check all these on H/V PSU you can be confident to connect the I/V board.

Salas should be set on around 5.3V so the shunt on the DAC board can have 0.3V to work with regulation accross the 10R resistor.
Don't need to load them for testing. If you want to, connect 100R (for 5.6V out)-180R (for 5.3V out) resistor for load. In this way you simulate +/- the current through 10R resistor before the 5V shunt on DAC board.
 
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#831
cheers.

The salas boars look very good on the scope, no ripple.

The heater supply is fine but does take a while to come up... does yours?

The HV supply is regulating well on the scope, sitting at 273v.

There is a tiny amount of chatter for about half a second. I think its related to the heater supply coming up, because a turn off then on without much wait means no chatter.

Its either that, or i remeber people having problems in the groupbuy for the b1 dc coupled buffer with chattering relay's. I seem to remeber a darlington instead of the npn was the cure.
 
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#832
apelizzo said:
Adamus don't rush to connect the boards to the two power supply before you tested them with load.
Step by step.

First you should test the HV fully loaded. Connect 2.2R+2.2R+2.2R+2.7R 5W each series on 270V. You must check with oscilloscope if the regulator is doing its job.
At the same time connect 2 10R 10W parallel to heater DC and check with oscilloscope you must not have ripple. You don't know if you don't check with oscilloscope.
You must load both heater and HV to make sure the transformer's internal regulation can maintain the sufficient voltage for both rails.
Your relay could chatter because ripple on 6.3V or relay too high voltage.
Relay must be 5V. It can work on 125% the nominal voltage so it forgives you.

After you check all these on H/V PSU you can be confident to connect the I/V board.

Salas should be set on around 5.3V so the shunt on the DAC board can have 0.3V to work with regulation accross the 10R resistor.
Don't need to load them for testing. If you want to, connect 100R (for 5.6V out)-180R (for 5.3V out) resistor for load. In this way you simulate +/- the current through 10R resistor before the 5V shunt on DAC board.
Click to expand...

Thanks yo you and Adamus for sharing your set up procedure. I'm still waiting for a few capacitors but are bookmarking your actions. Couple of questions:

Comments about using PIO (.1microF) as cathode bypass

Inherited 4 200microF Solen caps (they are huge) Is 200 too high for C5 on IV power supply?

Thanks

Bob
 
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