Is there a PCB pattern for infrared tach July 7 Servo?

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grant fair
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Is there a PCB pattern for infrared tach July 7 Servo?

Post by grant fair » Tue Aug 02, 2005 10:03 pm

Can anyone tell me if there is a PCB pattern included in the July 2005 Servo article on building an infrared tachometer?<p>(I have't found Servo on the newstands here)<p>Grant
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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by Rubi » Wed Aug 03, 2005 4:02 am

Hi Grant<p>I routed a pcb, but the tach does not work correctly in the moment, so I suggest there is an error in the circuit diagram.
I use smd and dil parts in my routing ( as I had found them in my toolbox) so if you are interested I can mail you the layout.
But be warned it does not jet work correctly.<p>Cheers
Rubi

grant fair
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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by grant fair » Wed Aug 03, 2005 9:32 pm

Thanks for your kind offer, Rubi. What software did you use to make your PCB pattern?<p>Grant
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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by Rubi » Thu Aug 04, 2005 6:34 am

Hi Grant<p>I used sprint layout.
www.abacom-online.de/uk/html/sprint-layout.html<p>I dont know if that is a popular choice over the ocean, in Europe it is, mostly used by amateurs like me.<p>I have a real problem with the UI of Eagle,...<p>There is a possibility to export the layout in
gerber, bitmap or gif.
If you want some minor routing changes tell me and I will implement them for you.<p>Meanwhile with the help from stephen, I think we tracked down the error in the schema, so I will inform you when it works.<p>Cheers
Michael

grant fair
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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by grant fair » Thu Aug 04, 2005 10:15 am

I am not familiar with the Sprint software. But I see that they have a demo viewer for Sprint files. That would simplify things, I guess. The other simple option for me would be a bitmap version of the PCB.<p>When you have the tach working I would be very happy to recieve a copy of the corrected PCB pattern.<p>I would likely copy it with the PCB software I use, Ivex, (which unfortunately went out of business).<p>Let me know when it is working and I'll pass on my email.<p>Grant
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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by grant fair » Thu Aug 04, 2005 7:09 pm

PS<p>Rubi-<p>Did you make your own PCB pattern because there is none in the Servo article? <p>Grant
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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by Rubi » Thu Aug 04, 2005 11:25 pm

Hi Grant<p>You wrote:
Did you make your own PCB pattern because there is none in the Servo article?<p>Yes and no, I did it, because I have so many Cmos ICs in the junkbox,and the project interested me.
But as you said there was no pcb and I hate to wire wrap my circuits,...<p>Cheers
Michael

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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by Edd » Mon Aug 15, 2005 7:24 pm

Michael and Grant...et al:
I viewed the schematic provided at the SERVO website and after a perusal of it, along with the reviewing of several comments that persons had already made about it. Since it seems known that at least two of you are attempting to construct it , plus I might have a future interest in it myself, I sat down and re-plotted the schematic. Keeping it in the original sizing utilized, but normally I plot up one or two clicks larger, since in the size utilized, it precludes most lower case font characters, being limited to a mere 5x3 pixels for text. Hopefully, it now has a more logical , free flowing order of the analog interfacing section of it , as well as cutting some partitioning line clutter from it. (Along with a forest of ground sprouts and power arrows). The neglected powering up of the IC8- 4001 was provided for, this time. Also, with the making of corrections to the mentioned detected flaws within the original schema, and a few that I also found. Additionally, utilizing the incorporation of good supply rail bypassing. There are several spare unused logic gates and op amps not utilized ...soooooo....I thought two nand gates were just crying to be utilized in a power shut off timer circuit, so I incorporated them within the schematic also. With this being a current hungry LED design, that would definitely be appreciated the first time a person forgets to turn the unit off after using it.
Another possibility of change was that sole IC9- 4017 counter, pulse driving the aiming LED driver xstr , it could have used a pair of the schmitt hex driver spares along with a delay timing intermediate R/C pair to fulfill its function.
Also, IMHO, this unit probably would be a good candidate to incorporate a visible red Laser pointer as the illumination source instead of the problematic (invisible) IR illumination source along with its additional baggage of support structure.
***Visible red laser pointers *** are now relatively economical......I would advise buying one price step level up from the cheapest devices that kids typically buy as "toys. ". The laser could then derive its power via a cross linked npn-pnp bipolar pair configured as a constant current source, then being adjustable for only using as much drive level as required in enacting the close range reflection. The reflected illumination being directionally channeled thru a 1 inch length of hobby shop K & S 1/16 brass tubing...flat black coated internally and externally....and mated to the head of the photo transistor. (I have not read the mechanics of the article and am not privy on the construction technique utilized by the originator.)
Hows about every one putting their eagle eyes...particularly Michael and Grant… since your feet are already wet... on this initial schematic and seeing if any further revisions/corrections ( Rev A thru ZZZ???) are needed:
:D<p>[ August 15, 2005: Message edited by: Edd Whatley ]</p>

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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by rshayes » Tue Aug 16, 2005 1:41 am

The power control circuit may have problems, since it is operating off of its own output.<p>Possibly one of the outputs of IC4 could be used for power off timing. The last divider will be operating at 1/512 Hz. This is over 8 minutes per cycle or 4 minute for a half cycle (to the first positive edge). You can get shorter times from the other taps.<p>Shouldn't the aiming LED be operated from the gate, so that it is off while a count is being made? Otherwise, the red light might be mixed with the infrared light and contaminate the count.<p>[ August 16, 2005: Message edited by: stephen ]</p>

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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by fernie7 » Mon Aug 22, 2005 2:13 pm

I am trying to build a tachometer/speedometer myself as a senior design project. Is the schematic attached a workable schematic. I am trying to build a digital warning speedometer that will drive an 8 ohm speaker when it hits 60 mph, then the tone increases every ten miles, 70, 80 and so on. I have done so much research but I can't seem to figure it out.
Thank you.

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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by philba » Mon Aug 22, 2005 10:12 pm

Fernie - While I admire the design of the circuit, it is 70s technology. The modern way to do this is with a microcontroller (and a cheap one at that). Also, you can avoid the opamps if you use either a phototransistor (photo interruptor or similar) or a hall effect device. You can run the output of those devices directly into the micro. All you need to do is count the number of rev/sec and translate that into distance (and thus speed). Then you emit the appropriate tone for the speed. <p>So, it's pretty much just a micro, the sensor and a low pass filter for the audio. Maybe an amplifier for the tone. I'd guess about $5 worth of parts or less...<p>Phil<p>[ August 23, 2005: Message edited by: philba ]</p>

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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by grant fair » Mon Sep 05, 2005 12:08 pm

Michael- have you got your PCB revised and working?<p>Edd - yo-yos with 500 foot strings? How are sales? Dropping off?<p>Grant
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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by Keyvan » Sun Sep 18, 2005 4:52 pm

Hi,<p>I am trying to design a warning speedometer and I would like to get some general idea. <p>Keyvan Jamaleddin
Aliasghar,[email protected]
Keyvan Jamaleddin
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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by jwax » Sun Sep 18, 2005 6:21 pm

Edd- How did the security/beam break IR diode system work? I'm curious that you felt confident in that tiny milliwatt IR diode to have much range at all. Was it scanning the land by a spinning mirror, or was the diode spinning? What kind of range could you achieve for detecting a person?
Reason I ask is there are lots of dead DVD players around, and it would be great to salvage their diodes and put them to use.
Thanks,
73's!
John

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Re: Is there a PCB pattern for infrared tach July 7 Servo?

Post by Robert Reed » Sun Sep 18, 2005 9:39 pm

Edd
refering to the auto shutoff cicuit:
The manual startup cicuit looks fine with diode and 10K resistor giving immediate startup bias to the 2N2905. But will the auto shutoff be able to sustain it self for the period of total circuit capacitve discharge (bypass C's , etc.) Also and I'm sure this was just an oversight, but the 2N2905 emitter-collector leads should be reversed. With this corrected, would the B-E laekage current (2N2905) thru Diode,10K,10MF path tend to turn this pass transistor back on after 10MF has sufficiently dischaged thru the cicuit loads (1 minute ?) Don't know what effect the unsupplied nand gates would have during this period.

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