Would you pay $100 for a HP6115A psu ?

[BravoV]

Edit :
The title is no longer relevant anymore since I scored it for $85, shot few photos at post #26 -> HERE, and this thread grows into discussions about this HP 6114/5A power supply.


Title should be self explanatory and would like to hear your opinion or suggestions if any, got an offer locally from a tech surplus shop.

I will have the luxury to inspect it physically and they allow me to bring my own DMM and load to verify it, but no internal inspection though. 

[Bored@Work]

In Europe yes, good deal.

[eevblogfan]

look ... no doubt ... very low noise high performance power supply , if you have the money , yea I would have , if that's needed of course ...

[sorin]

no
too old

[c4757p]

no
too old

Yes, it can't supply those new electrons we invented last year...
 

[robrenz]

The 6114A AND 6115A specs are extremely good.  try finding a modern supply this quiet or stable for less than several thousand dollars.  No current power supply by Agilent comes close until you spend over $5000.00 from what I have been able to find. The Power Designs Precision supplies are also in this category.
 $100.00 guaranteed working I think is a good deal.

[Jay_Diddy_B]

Hi,

You can read about the HP6114A which is very similar to the HP6115A in the HP Journal.

http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1972-11.pdf


The only downside to these supplies is the way the output voltage is controlled:



The use a constant current source into a decade resistor. If the switches are dirty the output voltage will jump.

There is an overvoltage crowbar (SCR) that can be used to protect your load.

The decade resistor contains some close tolerance resistors.



Jay_Diddy_B

[PedroDaGr8]

You also don't mention if it has the 10-turn Current Pot

[ivan747]

no
too old

Yes, it can't supply those new electrons we invented last year...
 

You always manage to brighten my day. But 30 year old electrons aren't the same as the newer ones, they are kinda slow. They get slower with time, I dunno.

I still like this supply. I would buy it if shipping wasn't a problem. Robrenz is right on the money. The specs are great, the resolution is good, the price... it always seems to be great. Please don't advertise this model around guys! And for god's sake don't let Dave make a video! Look what happened to the rubidium standards, they doubled the price since the video!

[BravoV]

Thanks for nay or yay sayers, your opinions are much appreciated. 

no
too old

I guess thats too brief. 

The 6114A AND 6115A specs are extremely good.  try finding a modern supply this quiet or stable for less than several thousand dollars.  No current power supply by Agilent comes close until you spend over $5000.00 from what I have been able to find. The Power Designs Precision supplies are also in this category.
 $100.00 guaranteed working I think is a good deal.

Yep, "mainly" this is your fault, especially after seeing your adventure with that fine 6114A of yours. 

I'm aware that it's accuracy might be drifted, but this can be calibrated. My main interest is the voltage range 0-100 Volt and the "stability factor", totally agree with your assessment, this beast definitely not an average adjustable lab psu performance at the price of $100.

Hi,

You can read about the HP6114A which is very similar to the HP6115A in the HP Journal.

The only downside to these supplies is the way the output voltage is controlled:

The use a constant current source into a decade resistor. If the switches are dirty the output voltage will jump.

There is an overvoltage crowbar (SCR) that can be used to protect your load.

The decade resistor contains some close tolerance resistors.

Jay_Diddy_B

Thanks for the link, yes, I'm aware of the mechanical switch weakness, but after reading Robrenz's work on his 6114A, I'm convinced, although I doubt my self to have the same level of skill in restoring old instruments as he did. 

How do you expect people to answer if you don't say what country you are in?  In the US you can get a better deal.

Nope, don't have the luxury of ebay-ing used T&M instruments from US, the cheapest shipping cost it self from US might be > $300. 

You also don't mention if it has the 10-turn Current Pot

The problem I have is the seller still can not find it in their warehouse. 

Will this 10 turns pot matter much ? Any chance of modding it my self ? What value of this current pot ?

I still like this supply. I would buy it if shipping wasn't a problem. Robrenz is right on the money. The specs are great, the resolution is good, the price... it always seems to be great. Please don't advertise this model around guys! And for god's sake don't let Dave make a video! Look what happened to the rubidium standards, they doubled the price since the video!

Nope, I will personally pick it up at the seller's warehouse.



Again, just to repeat, I will have the chance to inspect and test it physically, isn't this factor it self worth some pennies compared to online purchase ?


Quoted some of it's spec :

Constant voltage spec :
Load regulation : 0.0005% + 50uV
Line regulation : 0.0005% + 100uV
Ripple & noise : 40 uVrms/100uV p-p
Temp Co : 0.001% + 15uV
Drift (over 8 hours under load) : 0.0015% + 15uV
Transient recovery time : < 50uSec with 10mV of nominal output
Output impedance : 0.05 mOhm in series 3 uH inductor
Output voltage accuracy : 0.025% + 1mV

Constant current spec :
Load regulation : 0.01% + 500uA
Line regulation : 0.005% + 20uA
Ripple & noise : 200uA rms/1mA p-p
Temp Co : 0.02% + 25uA
Drift (over 8 hours under load) : 0.25% + 4mA

[PedroDaGr8]

Yeah you can add it manually later. It's a simple ten turn pot with a vernier dial. I'll see if I can give you the exact model number this weekend.

Personally I think it is worth $100. I have a 6114a and love it. The thing just exudes quality. The only thing comparable in this price range are the PD Precision supplies. They command a similar price range, though this one beats then on the spec sheet anyways.

Sent from my EVO using Tapatalk 4

[BravoV]

PedroDaGr8, thanks for the trouble.

Btw, do you have a particular photo shot at that pot where it installed ? Cause I don't see it at your HP 6114A teardown thread.

Looking at the schematic, is the current adjust pot has the value of 10 Ohm ? 

[PedroDaGr8]

PedroDaGr8, thanks for the trouble.

Btw, do you have a particular photo shot at that pot where it installed ? Cause I don't see it at your HP 6114A teardown thread.

Looking at the schematic, is the current adjust pot has the value of 10 Ohm ? 

it's mounted to the front where the current knob is on the regular version. It replaces the regular pot, with the regular knob replaced by a ten turn vernier dial.   As for the resistance value and model number I'll let you know this weekend

Sent from my EVO using Tapatalk 4

[robrenz]

Cheapest 10 turn 10 ohm pot I could find was $57.00 plus about $19.00 for a turns counting dial.  More than I paid for the power supply that had them. That does not mean this is a bad deal but if you have to spend $76.00 additional to get 10 turns it might influence your decision.  Many people don't realize how expensive the low ohms 10 turns can be.

[sync]

This is the current adjust pot. It has 1k. No problem finding a 10 turn one.

[robrenz]

You are correct, I assumed the previous posts were the correct pot. $10.00 now

[edavid]

Personally, I don't like the 10 turn current limit pot, because it takes forever to set it.  This is not a precision current source, after all.

[sync]

Use a 3 turn one.

But 0.01% load regulation for constant current mode is not bad at all for a power supply.

[robrenz]

6114A or 6115A is better or equal to the rigol dp832 Dave just looked at on current regulation and ripple.

6114A or 6115A at 0.8A  line and load reg. is max 0.08% same on the new Keithley 2450 SMU ($5400.00) line and load reg. is max 0.025%  Only 3 times better for 54X the money

This is a place where the Power Designs power supplies cannot compete. They were not designed for high accuracy current regulation, only general current limiting. They do not spec current regulation at all and testing I have done on the Power designs thread show they are very temperature sensitive on the current regulation.  A better TCR shunt may fix this problem but I have not had a chance to try it.  (PD fanboys relax, I have several of them )

[robrenz]

I just bought a 6115A today to keep my 6114A company.  It will need more TLC than the the 6114 did

[BravoV]

This is the current adjust pot. It has 1k. No problem finding a 10 turn one.

Thanks for spotting that !  Low resistance multiturns pot is really expensive as Robrenz mentioned.

I just bought a 6115A today to keep my 6114A company.  It will need more TLC than the the 6114 did

LOL ... when will this end Robrenz ? 

How is the new 6115A condition compared to the 6114A ? On the TLC, make another new restoration thread on this newly acquired beast please.

Btw, just an update, apparently this deal is on hold, cause the seller did a major warehouse restructuring and their merchandises were moved around, and this psu is still missing, probably buried somewhere. 

[robrenz]

I just bought a 6115A today to keep my 6114A company.  It will need more TLC than the the 6114 did

LOL ... when will this end Robrenz ? 

Someone has to keep your power supply thread going. I have spent less than the cost of 1 Rigol  DP832A and I have 8 independent floating power supplies that are more accurate, higher resolution, better stability, lower ripple. But I think I am done on power supplies. 8 (not counting the 2 BOSS bipolars) is plenty. 

How is the new 6115A condition compared to the 6114A ? On the TLC, make another new restoration thread on this newly acquired beast please.

Looks similar but with busted ground jack, power switch, and some of the panel markings look messed up. But for what I paid I can afford lots of TLC and a 10 turn 1k pot with turns counter.  I may do a video on the restoration.

[BravoV]

Someone has to keep your power supply thread going. I have spent less than the cost of 1 Rigol  DP832A and I have 8 independent floating power supplies that are more accurate, higher resolution, better stability, lower ripple. But I think I am done on power supplies. 8 (not counting the 2 BOSS bipolars) is plenty. 

Talking about digital age, actually I'm thinking to make a digital control module that provides adjustable reference voltage and also equipped with a dial or usb connectivity to be connected to these great old analog psus on their remote programming connectors in the back. Its like turning it into modern gadget  like current digital control PSUs while still have the proven performance and stability.


So the 6115A came without the 10 turns pot ? When you do the teardown, please take a shot especially at the 10t pot size and it's mounting location, cause there are many difference sizes for this kind of pot.

[robrenz]

Talking about digital age, actually I'm thinking to make a digital control module that provides adjustable reference voltage and also equipped with a dial or usb connectivity to be connected to these great old analog psus on their remote programming connectors in the back. Its like turning it into modern gadget  like current digital control PSUs while still have the proven performance and stability.

Great minds think alike

[robrenz]

6115A just arrived today.  Power switch was broken as listed but jumpering that it works fine. A standard 7/8" diameter 2W 10 turn will fit in the current limit pot location. (makes sense since it was an option anyway)