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HP 6012B volt zero and current regulation

 

Hello, I had a account from yahoo groups agilent and I recently transferred over.

I have a HP 6012B which I successfully repaired the current potentiometer so no more issue with the supply going full 60 amps with the slightest turn of the knob.

However I have some minor calibration issues if anyone could assist. I notice the volts on the display will not go below 0.2-0.1 volts at the full counter clockwise position, it also reads the same on the voltmeter. I am studying the manual to see where those adjustments are.

Also, when I test the amperage control by using a light bulb and a voltmeter in parallel to measure the current, if I set the current to 4 amps and quickly ramp the voltage the current peaks at 5 amps briefly before going back down to 4 amps a fraction of a second later. Could this be a typical overshoot characteristic of this supply?

Thanks
 

NO This is the typical behaviour of a light bulb,

73 George G6HIG


On Sunday, August 19, 2018 10:40 PM, "wilson2115@..." <wilson2115@...> wrote:


Hello, I had a account from yahoo groups agilent and I recently transferred over.

I have a HP 6012B which I successfully repaired the current potentiometer so no more issue with the supply going full 60 amps with the slightest turn of the knob.

However I have some minor calibration issues if anyone could assist. I notice the volts on the display will not go below 0.2-0.1 volts at the full counter clockwise position, it also reads the same on the voltmeter. I am studying the manual to see where those adjustments are.

Also, when I test the amperage control by using a light bulb and a voltmeter in parallel to measure the current, if I set the current to 4 amps and quickly ramp the voltage the current peaks at 5 amps briefly before going back down to 4 amps a fraction of a second later. Could this be a typical overshoot characteristic of this supply?

Thanks


Dr. David Kirkby from Kirkby Microwave Ltd
 

On Sun, 19 Aug 2018 at 22:45, george edmonds via Groups.Io <G6HIG=[email protected]> wrote:
NO This is the typical behaviour of a light bulb,

73 George G6HIG

Sure a lightbulb draws more current when cold, but if I understand the original poster correctly, he has set a current limit of 4 A on the PSU, so one would not expect to be able to get 5 A from it, even with a dead short. Without a detailed looked at the specifications, it is hard to know what is normal and what is not.

There are some pretty beefy FETs around with a low on-resistantance, which could be driven with a function generator to quickly (or slowly) change the load resistance.


--
Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD, Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892

Tel 01621-680100 / +44 1621-680100
 

I took a look at the for this supply, if I read correctly the regulation is within 10mA and 5mV, quite good.

I have a HP 6024A supply which I will try this test on.
 

The test results from the HP 6024 supply revealed that when the current is limited to 4 amps with the same setup from the 6012B, ramping up the voltage to test the current regulation it immediately stops at 4 amps although I notice a slight blip in brightness from the bulb, but not as bright or as long as noticed on the 6012B. I am studying the manual but at least I confirmed there is no phenomenons occurring with my test setup.
Dr. David Kirkby from Kirkby Microwave Ltd
 

On Sun, 19 Aug 2018 at 23:20, <wilson2115@...> wrote:
The test results from the HP 6024 supply revealed that when the current is limited to 4 amps with the same setup from the 6012B, ramping up the voltage to test the current regulation it immediately stops at 4 amps although I notice a slight blip in brightness from the bulb, but not as bright or as long as noticed on the 6012B. I am studying the manual but at least I confirmed there is no phenomenons occurring with my test setup.

I don't think you should equate brightness with current, as you have a non-linear device. I would personally be observing the current with a scope, not judging it by a lightbulb. A FET fed with a square wave generator would make a load that should allow you to see the step response.

--
Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD, Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892

Tel 01621-680100 / +44 1621-680100
 
Edited

I am using a fluke voltmeter to measure the current using the peak measurement, is that a reliable indication of regulation by voltmeter?

I had an idea. If anyone has a 6012B, maybe 6012A, or a 6032A. Perhaps through a power resistor or bulb, to simulate the results I am observing. Set the current to a specific value and then rapidly ramp up the voltage and observe the regulation effects. If we conclude that you observe similar results to me this is then typical, if not post your results so I can compare with mine. I assume the 6012A and 6032A are similarly designed power supplies?

I observe when setting 4 amps only the supply and the voltage quickly ramped there is a peak of 4.8 amps under a load from a bulb, precisely its a car headlight

I should add this is not critical but just a observation and I am comparing my results to others.
 

I refined my test...
Instead of ramping the voltage with the knob. I basically set the voltage to 20V and the amperage to 2 amps. I connected the voltmeter in series with the bulb and performed a dynamic load test by opening and closing the circuit by touching the probe lead of the voltmeter to the output of the power supply... I also have the Fluke voltmeter set to peak amperage measurement and these are the results that I found.

With the 6012B set to 20V and 2A, upon closing the circuit the peak amps are 4 amps but quickly settles to 2 amps
With the 6024A set to 20V and 2 A, upon closing the circuit the peaks amps are about 2.5 but quickly settles to 2 amps.

The important observation here is the 6012B settles back to 2 amps, it seems the settle time is longer and the deviation is larger than the 6024A. Although these are two completely different supplies. If anything I could be nit picking here on the 6012B for its regulation settle time and overshoot, which is why I wanted to see if someone else had a similar supply and could see if they could duplicate the same results to see if this is normal...

Thanks for the help
 

Hi

In my experience most bench power supplies show a similar behaviour. ?At one time I suffered repeated damage to equipment that was powered from a bench supply, when checked with a storage scope it went to a high voltage on turn on before settling back to the set voltage.

I still think that for valid measurements you cannot use a light bulb, they are NOT a linear devices if you do an applied voltage plot against observed resistance, from a sixtey year old memory of an experiment they are square law devices

73 George G6HIG ??



On Monday, August 20, 2018 5:50 PM, "wilson2115@..." <wilson2115@...> wrote:


I refined my test...
Instead of ramping the voltage with the knob. I basically set the voltage to 20V and the amperage to 2 amps. I connected the voltmeter in series with the bulb and performed a dynamic load test by opening and closing the circuit by touching the probe lead of the voltmeter to the output of the power supply... I also have the Fluke voltmeter set to peak amperage measurement and these are the results that I found.

With the 6012B set to 20V and 2A, upon closing the circuit the peak amps are 4 amps but quickly settles to 2 amps
With the 6024A set to 20V and 2 A, upon closing the circuit the peaks amps are about 2.5 but quickly settles to 2 amps.

The important observation here is the 6012B settles back to 2 amps, it seems the settle time is longer and the deviation is larger than the 6024A. Although these are two completely different supplies. If anything I could be nit picking here on the 6012B for its regulation settle time and overshoot, which is why I wanted to see if someone else had a similar supply and could see if they could duplicate the same results to see if this is normal...

Thanks for the help


 

¿ªÔÆÌåÓý

Off subject ¨C I still get duplicates ¨C Joel STS SS

?

From: [email protected] [mailto:[email protected]] On Behalf Of wilson2115@...
Sent: Monday, August 20, 2018 12:50 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 6012B volt zero and current regulation

?

I refined my test...
Instead of ramping the voltage with the knob. I basically set the voltage to 20V and the amperage to 2 amps. I connected the voltmeter in series with the bulb and performed a dynamic load test by opening and closing the circuit by touching the probe lead of the voltmeter to the output of the power supply... I also have the Fluke voltmeter set to peak amperage measurement and these are the results that I found.

With the 6012B set to 20V and 2A, upon closing the circuit the peak amps are 4 amps but quickly settles to 2 amps
With the 6024A set to 20V and 2 A, upon closing the circuit the peaks amps are about 2.5 but quickly settles to 2 amps.

The important observation here is the 6012B settles back to 2 amps, it seems the settle time is longer and the deviation is larger than the 6024A. Although these are two completely different supplies If anything I could be nit picking here on the 6012B for its regulation settle time and overshoot, which is why I wanted to see if someone else had a similar supply and could see if they could duplicate the same results to see if this is normal...

Thanks for the help

 

¿ªÔÆÌåÓý

Also many bench supplies have very large output capacitors. I have a smaller HP on my bench and recorded over 100 amps instantaneous on a short with a couple feet of #10 leads. That was all from the output cap, it¡¯s a 10 amp supply.?


Peter

On Aug 20, 2018, at 2:18 PM, george edmonds via Groups.Io <G6HIG@...> wrote:

Hi

In my experience most bench power supplies show a similar behaviour. ?At one time I suffered repeated damage to equipment that was powered from a bench supply, when checked with a storage scope it went to a high voltage on turn on before settling back to the set voltage.

I still think that for valid measurements you cannot use a light bulb, they are NOT a linear devices if you do an applied voltage plot against observed resistance, from a sixtey year old memory of an experiment they are square law devices

73 George G6HIG ??



On Monday, August 20, 2018 5:50 PM, "wilson2115@..." <wilson2115@...> wrote:


I refined my test...
Instead of ramping the voltage with the knob. I basically set the voltage to 20V and the amperage to 2 amps. I connected the voltmeter in series with the bulb and performed a dynamic load test by opening and closing the circuit by touching the probe lead of the voltmeter to the output of the power supply... I also have the Fluke voltmeter set to peak amperage measurement and these are the results that I found.

With the 6012B set to 20V and 2A, upon closing the circuit the peak amps are 4 amps but quickly settles to 2 amps
With the 6024A set to 20V and 2 A, upon closing the circuit the peaks amps are about 2.5 but quickly settles to 2 amps.

The important observation here is the 6012B settles back to 2 amps, it seems the settle time is longer and the deviation is larger than the 6024A. Although these are two completely different supplies. If anything I could be nit picking here on the 6012B for its regulation settle time and overshoot, which is why I wanted to see if someone else had a similar supply and could see if they could duplicate the same results to see if this is normal...

Thanks for the help


 

?
During 10 years or so doing life tests on transistors in the 1960s and 70s I would not use regulated power supplies for powering the devices during their life test. When asked, I demonstrated the switch on pulse with a Tek storage scope. ok it was only microseconds wide but peaked at the unregulated level.~35v .....enough to damage 24v transistors.This can also happen with a transcient load. It is to do with the bandwidth of the feedback loop.
?
Alan
G3NYK
?

----- Original Message -----
Sent: Monday, August 20, 2018 7:18 PM
Subject: Re: [HP-Agilent-Keysight-equipment] HP 6012B volt zero and current regulation

Hi

In my experience most bench power supplies show a similar behaviour. ?At one time I suffered repeated damage to equipment that was powered from a bench supply, when checked with a storage scope it went to a high voltage on turn on before settling back to the set voltage.

I still think that for valid measurements you cannot use a light bulb, they are NOT a linear devices if you do an applied voltage plot against observed resistance, from a sixtey year old memory of an experiment they are square law devices

73 George G6HIG ??



On Monday, August 20, 2018 5:50 PM, "wilson2115@..." <wilson2115@...> wrote:


I refined my test...
Instead of ramping the voltage with the knob. I basically set the voltage to 20V and the amperage to 2 amps. I connected the voltmeter in series with the bulb and performed a dynamic load test by opening and closing the circuit by touching the probe lead of the voltmeter to the output of the power supply... I also have the Fluke voltmeter set to peak amperage measurement and these are the results that I found.

With the 6012B set to 20V and 2A, upon closing the circuit the peak amps are 4 amps but quickly settles to 2 amps
With the 6024A set to 20V and 2 A, upon closing the circuit the peaks amps are about 2.5 but quickly settles to 2 amps.

The important observation here is the 6012B settles back to 2 amps, it seems the settle time is longer and the deviation is larger than the 6024A. Although these are two completely different supplies. If anything I could be nit picking here on the 6012B for its regulation settle time and overshoot, which is why I wanted to see if someone else had a similar supply and could see if they could duplicate the same results to see if this is normal...

Thanks for the help


 



On Mon, Aug 20, 2018, 14:22 Joel R Kist <joel-kist@...> wrote:

Off subject ¨C I still get duplicates ¨C Joel?


By chance are you subscribed to the group with two different email addresses? Check the headers of the emails that are dupes the next time you receive them.?

Mark
 

¿ªÔÆÌåÓý

I did a lot of power supply testing for HP, Agilent, and NGC, including the 6012A/B¡¯s,
Here is the spec sheet:?. ?What you want to look at is the transient response - right hand column. ?Calibration transient response is tested for both voltage and current modes and is tested full to no resistive load, and also with 100/90% resistive load change. ?2ms/100mv. ?I believe that a min. 5 min. warmup time is required for specs to apply.
Don Bitters
 

¿ªÔÆÌåÓý

OK, I'll bite--

What kind of power supply would you recommend?? I always thought that a regulated supply would be the safest.?

Were these linear or switcher supplies that produced the spikes?

Thanks,

Dave


On 8/20/2018 2:31 PM, Alan Melia via Groups.Io wrote:

During 10 years or so doing life tests on transistors in the 1960s and 70s I would not use regulated power supplies for powering the devices during their life test. When asked, I demonstrated the switch on pulse with a Tek storage scope. ok it was only microseconds wide but peaked at the unregulated level.~35v .....enough to damage 24v transistors.This can also happen with a transcient load. It is to do with the bandwidth of the feedback loop.
?
Alan
G3NYK
 

Hi Dave. I got to thinking a bit about the point Alan made below, and
it's a very good one. If you consider the turn-on behavior of an
unregulated linear supply (i.e. the classic transformer, bridge
rectifier, filter capacitor construct), the shape of the voltage ramp-up
curve should be dominated by the capacitor's charging characteristics.
But if you place a regulator after that, the output voltage (of the
regulator) will rise, and go potentially quite high above the setpoint
until the regulation loop takes over. The width of the waveform above
the setpoint voltage will correspond in inverse proportion to the
bandwidth of the control loop of the regulator.

Linear and switching regulators will both exhibit this behavior,
though modern switching regulators with high switching frequencies and
high-bandwidth control loops will keep it well under control.

In practice this is usually so brief that it doesn't bother anything,
a few dozen microseconds at most. I myself have watched it on an
oscilloscope (I design and characterize a lot of voltage regulators) but
have never seen it do any harm.

-Dave

On 08/20/2018 05:06 PM, David Speck wrote:
OK, I'll bite--

What kind of power supply would you recommend?? I always thought that a
regulated supply would be the safest.?

Were these linear or switcher supplies that produced the spikes?

Thanks,

Dave


On 8/20/2018 2:31 PM, Alan Melia via Groups.Io wrote:
During 10 years or so doing life tests on transistors in the 1960s and
70s I would not use regulated power supplies for powering the devices
during their life test. When asked, I demonstrated the switch on pulse
with a Tek storage scope. ok it was only microseconds wide but peaked
at the unregulated level.~35v .....enough to damage 24v
transistors.This can also happen with a transcient load. It is to do
with the bandwidth of the feedback loop.
?
Alan
G3NYK
--
Dave McGuire, AK4HZ
New Kensington, PA
 

?
One that doesnt give spikes :-))? Any supply with feedback linear or switcher is a potential spike producer !
?
I am not up to date in this area it is possible that slow-start supplies might be best. Other members may have more ideas.
?
Alan
G3NYK

----- Original Message -----
Sent: Monday, August 20, 2018 10:06 PM
Subject: Re: [HP-Agilent-Keysight-equipment] HP 6012B volt zero and current regulation

OK, I'll bite--

What kind of power supply would you recommend?? I always thought that a regulated supply would be the safest.?

Were these linear or switcher supplies that produced the spikes?

Thanks,

Dave


On 8/20/2018 2:31 PM, Alan Melia via Groups.Io wrote:
During 10 years or so doing life tests on transistors in the 1960s and 70s I would not use regulated power supplies for powering the devices during their life test. When asked, I demonstrated the switch on pulse with a Tek storage scope. ok it was only microseconds wide but peaked at the unregulated level.~35v .....enough to damage 24v transistors.This can also happen with a transcient load. It is to do with the bandwidth of the feedback loop.
?
Alan
G3NYK
 

¿ªÔÆÌåÓý

You¡¯re probably subscribed on two different emails that end up at the same place.?

20 aug. 2018 kl. 14:22 skrev Joel R Kist <joel-kist@...>:

Off subject ¨C I still get duplicates ¨C Joel STS SS

?

From: [email protected] [mailto:[email protected]] On Behalf Of wilson2115@...
Sent: Monday, August 20, 2018 12:50 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP 6012B volt zero and current regulation

?

I refined my test...
Instead of ramping the voltage with the knob. I basically set the voltage to 20V and the amperage to 2 amps. I connected the voltmeter in series with the bulb and performed a dynamic load test by opening and closing the circuit by touching the probe lead of the voltmeter to the output of the power supply... I also have the Fluke voltmeter set to peak amperage measurement and these are the results that I found.

With the 6012B set to 20V and 2A, upon closing the circuit the peak amps are 4 amps but quickly settles to 2 amps
With the 6024A set to 20V and 2 A, upon closing the circuit the peaks amps are about 2.5 but quickly settles to 2 amps.

The important observation here is the 6012B settles back to 2 amps, it seems the settle time is longer and the deviation is larger than the 6024A. Although these are two completely different supplies If anything I could be nit picking here on the 6012B for its regulation settle time and overshoot, which is why I wanted to see if someone else had a similar supply and could see if they could duplicate the same results to see if this is normal...

Thanks for the help

 

I made a constant current load at work, 100 amps 200 volts, of course with a control loop.? When first connected the loop is calling for max current and it made a big current spike.? As this was annoying (making cables jump), I changed it to have a slow start ramp, taking a second to ramp up.? That was pretty easy so I imagine it shouldn't be a problem making a voltage mode supply do the same, and I would expect any decent one to behave that way.

All that was said about control loops is true, you can't get out of that, it's all about the loop bandwidth and also every regulated supply has a particular response, which may be critically, under or over damped.? I have absolutely seen supplies ring in response to a transient load change.? I have also seen really really bad power supply behavior like a 40 volt 20 amp Harrison HP bench supply go severely overvoltage - completely wide open - when a noisy load was applied.? I literally GAVE that supply away.

On 8/20/2018 6:10 PM, Alan Melia via Groups.Io wrote:
?
One that doesnt give spikes :-)) Any supply with feedback linear or switcher is a potential spike producer !
I am not up to date in this area it is possible that slow-start supplies might be best. Other members may have more ideas.
Alan
G3NYK

----- Original Message -----
*From:* David Speck <mailto:Dave@...>
*To:* [email protected]
<mailto:[email protected]>
*Sent:* Monday, August 20, 2018 10:06 PM
*Subject:* Re: [HP-Agilent-Keysight-equipment] HP 6012B volt zero and
current regulation

OK, I'll bite--

What kind of power supply would you recommend?? I always thought that a
regulated supply would be the safest.

Were these linear or switcher supplies that produced the spikes?

Thanks,

Dave


On 8/20/2018 2:31 PM, Alan Melia via Groups.Io wrote:
During 10 years or so doing life tests on transistors in the 1960s and
70s I would not use regulated power supplies for powering the devices
during their life test. When asked, I demonstrated the switch on pulse
with a Tek storage scope. ok it was only microseconds wide but peaked at
the unregulated level.~35v .....enough to damage 24v transistors.This can
also happen with a transcient load. It is to do with the bandwidth of the
feedback loop.
Alan
G3NYK
 

¿ªÔÆÌåÓý

Hello,

all I do know is that Rohde released, some years ago, a "capacitorless" power supply.


Tam

With best regards
Tam Hanna
---

Enjoy electronics? Join 8300 other followers by visiting the Crazy Electronics Lab at
On 21.08.2018 00:10, Alan Melia via Groups.Io wrote:

One that doesnt give spikes :-))? Any supply with feedback linear or switcher is a potential spike producer !
?
I am not up to date in this area it is possible that slow-start supplies might be best. Other members may have more ideas.
?
Alan
G3NYK
----- Original Message -----
Sent: Monday, August 20, 2018 10:06 PM
Subject: Re: [HP-Agilent-Keysight-equipment] HP 6012B volt zero and current regulation

OK, I'll bite--

What kind of power supply would you recommend?? I always thought that a regulated supply would be the safest.?

Were these linear or switcher supplies that produced the spikes?

Thanks,

Dave


On 8/20/2018 2:31 PM, Alan Melia via Groups.Io wrote:
During 10 years or so doing life tests on transistors in the 1960s and 70s I would not use regulated power supplies for powering the devices during their life test. When asked, I demonstrated the switch on pulse with a Tek storage scope. ok it was only microseconds wide but peaked at the unregulated level.~35v .....enough to damage 24v transistors.This can also happen with a transcient load. It is to do with the bandwidth of the feedback loop.
?
Alan
G3NYK

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