Am new to the board and would like to ask 2 questions. Does anyone remember back when Heathkit actually made kits?! What's up with that? I used to rely on their kits for several projects I did. They were well built, well documented and I learned alot from them! Oh well... is there anyone following in their footsteps?
Question number 2... I am in the process of building a test bay for some equipment we manufacture. We have to electronically "tune" each piece, and I have inherited a test bay with simpson panel meters and a radio-shack built test-jig that simply serves to switch pin voltages to the "test jig" meter. I'd like to replace the test-jig and switch with three more panel meters and just read the voltages simultaneously. The idea is to simplify the test, and get rid of a possible point of failure. I need to find a good simple plan for a digital volt meter (dc - low volts and ac low volts) that I can build cheaper than adding 3 new simpson panel meters. I also need these to be calibratable (I have a calibrated, NIST traceable Fluke, and will use it to calibrate the panel meters). Any ideas?
I remember Heathkit -- I still have (and use) a single- channel 5MHz oscilloscope (one of their kits I built some 2 decades ago)
~~ I once saw this kit 'scope on an episode of Blake's Seven (space soap) so they will still be available in the future :lol:
I guess from your ref. to NIST that you are in USA? No point in suggesting www.maplin.co.uk then?
A liquid crystal digital panel meter is available - 0 to 200mV, 3 1/2 digit display, 1000Meg input impedance, 9 to 12v supply. £17. (order code GW01B)
You're right, Velleman's is great! As far as what I am looking for they come close. I'm really looking for a simple schematic for something that will show more than 3 digits though. I'll continue to look and if I DO find something, I'll post it here.
Yes, I am in the US. The meters will be used in a final test of some equipment we build for others. I need to make sure that I can calibrate the meter, so that it's in spec according to NIST.
Just dug out a data sheet for a 3 1/2 digit panel meter IC (available as LED display -7107 and Liquid Crystal display - 7106). Both options have auto-zero and auto-polarity. The data sheet (dated 1984!) even shows an op-amp circuit for a presision rectifier to measure AC!
Half - a - dozen capacitors, some resistors and a preset and you're there
Drop me a [PM] with your email address if you want a copy scanning and sending to you... or should a circuit like this be added to the PROJECTS section :?:
I have used this IC before for 4.5 digit meters and it is excellent and easy to implement - ICL7129 / MAX7129. Its a 4.5 digit LCD driver with built in ADC so you only need a few extra parts.
The part is available from Maxim and if you look on their website and enter your company details they will even send samples of the requested IC, these usually only take a few days to the UK so from within the USA will be even quicker. Heres the sheet.
I have used this IC before for 4.5 digit meters and it is excellent and easy to implement - ICL7129 / MAX7129. Its a 4.5 digit LCD driver with built in ADC so you only need a few extra parts.
The part is available from Maxim and if you look on their website and enter your company details they will even send samples of the requested IC, these usually only take a few days to the UK so from within the USA will be even quicker. Heres the sheet.
That is reasonable if the new post is directly related to the original thread or adds to the context of the thread.
But a recent example was a "one post wonder" asking "can I get a circuit board layout" for a circuit in a thread which is five years old.
Not a sensible request in my opinion.