7 volt DC standard based on the HP/Agilent 03458-66509 LTZ1000 reference board - Page 1
Forum section: electronics / testgear

author: Awesome14
author_rank: Regular Contributor
timestamp: May 11, 2015, 07:07:28 pm
content: I built 2 DC standards according tohttp://www.maxmcarter.com/vref/,with a few tweaks on the power supply. I ran the -15VDC regulator (LM7915) off the adjustable regulator (LM317), skipped the rectifier circuit, and added ripple reduction and stability measures according to the LM317 and LM7915 data sheets. The total cost was about USD200.00 for parts for each unit.The reference board used--the HP/Agilent 03458-66509--is the internal DC voltage reference used in the HP/Agilent/Keysight 3458A 8.5 digit DMM.The results were disappointing. After insulation was added to the regulator IC (LTZ1000), and the board was installed in an enclosure, the best it could do was about 0.5ppm/degreeC, and +-5ppm accuracy, which is pretty poor for the LTZ1000. It seems as though HP/Agilent did not fully exploit the LTZ1000, but instead built a reference for the 3458A that was just good enough. The meter is spec'ed at +-6ppm, and that's about what this reference does.Sorry for the bad news. But if you want to fully exploit the LTZ1000 regulator IC, the HP reference board for the 3458A is not going to do it.

author: MadTux
author_rank: Frequent Contributor
timestamp: May 11, 2015, 07:14:52 pm
content: They forgot to pray.And of course HP sucks.They forgot magic copper foil thermal compensation in their instruments

author: HighVoltage
author_rank: Super Contributor
timestamp: May 11, 2015, 07:27:58 pm
content: Here we go again ...

author: Awesome14
author_rank: Regular Contributor
timestamp: May 12, 2015, 03:57:00 am
content: Quote from: MadTux on May 11, 2015, 07:14:52 pmI think you're the one who forgot to pray. The just fall seven times and rise again each time. The arrogant, ignorant and blind stumble to their ruin. For them, fate comes in a moment. The more you antagonize the righteous, the more suffering you store up for your end. I might add that you do what you do out of spiteful wickedness intrinsic to yourself.

author: Awesome14
author_rank: Regular Contributor
timestamp: May 12, 2015, 04:04:42 am
content: Quote from: HighVoltage on May 11, 2015, 07:27:58 pmAnd you, I thought you might be above this sort of thing. I guess you're stuck in the same prison as MT. Both of you exist under my control. You just can't help it.

author: deadlylover
author_rank: Frequent Contributor
timestamp: May 12, 2015, 07:30:11 am
content: HP ran their reference quite hot(95C) to get their stated 55C operating temp of the 3458A, you can get much better drift if you bring the LTZ1000 heater down to 65C.

author: paulie
author_rank: Frequent Contributor
timestamp: May 12, 2015, 12:03:51 pm
content: Quote from: Awesome14 on May 12, 2015, 03:57:00 amQuote from: Awesome14 on May 12, 2015, 04:04:42 amHere we REALLY go again ...Awesome, do you never learn?

author: Awesome14
author_rank: Regular Contributor
timestamp: May 13, 2015, 01:27:36 am
content: Quote from: deadlylover on May 12, 2015, 07:30:11 amThanks. I'll try that. I assume the DIP-8 opamp is the oven control.

author: Awesome14
author_rank: Regular Contributor
timestamp: May 13, 2015, 01:53:05 am
content: Quote from: paulie on May 12, 2015, 12:03:51 pmUnfortunately I was a few steps behind. What HV must have meant was, "Here we go again! He built something else without help from the community." If I require assistance, I'm not shy about asking.And you were once a voice of reason! What happened!Upon reflection, I was wrong to post on this board again. I don't require recognition. And I sure as hell don't need the headache. So, I did learn something.

author: dadler
author_rank: Unknown
timestamp: May 13, 2015, 01:54:25 am
content: Can someone lock this thread ?

author: paulie
author_rank: Frequent Contributor
timestamp: May 13, 2015, 02:15:35 am
content: Quote from: Awesome14 on May 13, 2015, 01:53:05 amUnfortunately it's hard to say the same about yourself sometimes. I merely suggest you might tone down the mystical rhetoric. You have enemies based solely on gang instinct and personal prejudice so why give them fuel for the fire. Sacrifice at the stake not appreciated by all.This is not a bad thread. Already learned a couple things and a shame to see it fall victim to another feeding frenzy.