HP 45 High Precision Timer
|
09-21-2015, 08:45 AM
(This post was last modified: 10-13-2015 11:36 AM by Sadsilence.)
Post: #4
|
|||
|
|||
RE: HP 45 High Precision Timer
(09-20-2015 09:48 PM)cruff Wrote: Well strictly speaking, if you an afford to order the minimum batch size, many crystal manufacturers will custom manufacture some for you. :-) You can order a 7.8432 MHz crystal off DigiKey, run it through a divide by 10 and only be slightly fast. Of course you are right. I checked such opportunities, too. In the end, they are either too expensive or too complex or needs too much power or a combination of all. If there is a real demand of 784 kHz crystals, there would be a lot of manufactures. A customs design in 100 pieces range is beyond any reasonable budget. Anything else but a matching crystal requires additional electronic parts. When using preprogrammable oscillators an output level adaption would be necessary. But it is like they try to tease HP-45 owners ;-). Free available chips with preprogrammable frequencies below 1 MHz are rare. The parts in right frequency range are either in wrong supply range, have housings, not manageable for private use or require > 10 mA. Programmable devices, I include your base frequency divide idea in that category, requires even more parts. Counter/Shifters with a lot of pins for frequency dividing, a precise voltage reference for VCOs or even a microcontroller for PLL stuff or oscillators with a programming interface and, when one chip is not able to handle 3.6 - 4.5V, a voltage regulation circuit. Besides limited space inside HP-45 you have to develope a special PCB... Another problem is extreme accuracy when it comes to time measurement. 0.1% or 1% tolerances of devices (resisitors etc.) are normally regarded as very good. For a everyday timer 0.01% is regarded as "ok". Of course, I would be glad, if there is an easier solution or I missed a 784 kHz crystal source or I understand HP-45 curcuits wrong. Feedback is highly appreciated. Best regards, Werner |
|||
« Next Oldest | Next Newest »
|
Messages In This Thread |
HP 45 High Precision Timer - Sadsilence - 09-20-2015, 06:44 PM
RE: HP 45 High Precision Timer - Etienne Victoria - 09-20-2015, 08:21 PM
RE: HP 45 High Precision Timer - cruff - 09-20-2015, 09:48 PM
RE: HP 45 High Precision Timer - Sadsilence - 09-21-2015 08:45 AM
RE: HP 45 High Precision Timer - cruff - 09-21-2015, 05:58 PM
RE: HP 45 High Precision Timer - Sadsilence - 09-21-2015, 08:21 PM
RE: HP 45 High Precision Timer - Duane Hess - 10-11-2015, 11:18 AM
HP 45 Timer - Sadsilence - 10-13-2015, 02:48 PM
RE: HP 45 High Precision Timer - TASP - 10-14-2015, 02:37 AM
RE: HP 45 High Precision Timer - Sadsilence - 10-28-2015, 10:51 PM
RE: HP 45 High Precision Timer - Etienne Victoria - 11-14-2015, 04:51 PM
RE: HP 45 High Precision Timer - Sadsilence - 11-14-2015, 08:08 PM
RE: HP 45 High Precision Timer - Sadsilence - 05-31-2017, 08:07 PM
|
User(s) browsing this thread: 1 Guest(s)