THE MISTAKEN "COIN HAWK PROTEL SCHEMATIC"

[Sasho- Bulgaria]

I found these mustakes:

[Sasho- Bulgaria]

This schematic works well:

[ivconic]

....


Many thanks Sasho!
I already corrected audio....i'll correct other two and than post results!
regards!

[Sasho- Bulgaria]

This schematic will work well:

[sisco]

HI Sasho

you make this and test or not?

[Sean_Goddard]

WOW, This WAS the idea in the first place. To get others to built test and IMPROVE the design. I see my inexperience with Protel put a few errors in the schematic like shorts in places.. SORRY GUYS!!

The 12V Tx was to boost the output power and see what the result was. If you can get it to work using this 12V on the TX then you need the "dropper" resistors R19/R22 if you use Vdd then remove these or the zero X'ing detectors will not work properly due to insufficient drive I think.

Let me know if this works when you have finished building (IF you build it) please. Well done for spotting my silly mistakes.

[rdec4]

I don't see the corrected schematics .
Please, publish them again.

[porkluvr]

In Work

Hello rdec4:

I worked on some of the errors back in July, and this is a picture of my "final" edit in Altium. After some months of being without, I reloaded Altium on my PC last night and I will begin in ernest to try and (re)gain some proficiency with the behemoth. (I use Eagle most of the time. It's slightly buggy, but SIMPLE.) Altium has a steep learning curve - and my skill needs some time for refreshing.

There may be some more circuit errors, and I will look. But also, I think the Coinhawk would benefit from a Battery-Low indicator. After I work it in, I will post the resulting Altium schematic. I don't know that you will be able to use Protel to open it, though - if that's what you are after. Sorry.

I do not guarantee that my "final" edit is not full of errors, so watch out.

I'll probably be back in a day or two.

[rdec4]

Hello porkluvr,

Thanks a lot for the schematic.
I use Altium. It's a world the best electronic development system.
I wating your last schematic revision in Altium Designer format.

[porkluvr]

CoinHawk update

This is Shawn Goddard's design, called "Coinhawk". There were some defects that crept into some of the earlier drawings that I hope to have corrected. I made some non-essential changes that are documented, in case you want to un-do my work.

I have added a Low-Battery alarm LED flasher. Component values are geared towards using two 7.2V NiMH batteries. Deep discharging NiMH will damage them, hence the need for a low-battery indicator. The trip point should be tailored for whatever type battery you use. I think 14.1V is about right for (2x)NiMH. There is not a big difference between the voltage of a "good" NiMH battery and one that needs charging, so setting the trip point may be tricky. Here, the trip point is adjustable from about 13V to 15V. NiCad batteries may also be accomodated.

My flasher is untested, but spice simulation looks good. I took a Dave Johnson and Associates design off the internet and modified it. 1/2 LM358 works OK as the comparator. Low battery voltage causes U1b to supply -5V to the flasher. The 120R may be adjusted to accomodate different LEDs.

The flasher was originally designed for 3V operaration. Instead of added complication we can use a 5V supply and increase the current limiting resistor. I added some capacitors to limit transient spikes.

In the speaker drive circuit - I realize that using a zener diode in series connection is not normal, but all I wanted was a voltage drop and isolation from the battery (and the regulated voltages). Regulation is not intended. The selection of Zener voltage is not particularly critical. 14.2V minus Zener voltage is applied to the audio section. IN755 is a 7.5V device. Because of R16 voltage drop, speaker drive "overhead" depends on the speaker used. I would use a 16 or 32 ohm speaker or more, but you do what you do.
***********************************************
I am not very competent with Altium and I created some of the components used in the schematic, - so there may be problems. Actually, there certainly will be problems for anyone wanting to convert this schematic to a PCB. Footprints will be missing. Component pin-outs may even be incorrect. If you wait on me to gain enough proficiency to correct all errors and clean up completely, you will probably be waiting a long time.

To anybody wanting to build this project: proceed with care. I have used this project more of an exercise and learning tool than anything practical, and I have other projects to finish before this one. If you know how to use Altium PCB, then you are ahead of me, so have at it! I am not so proficient.

There are inconsistencies present in the drawing: I created a potentiometer, designated "RV". The majority of pots were already present in the design and are designated "R". I say 2u2 instead of 2.2uF, and 2k2 instead of 2.2k. So, you will find annotation anomalies. There will be other inconsistencies. These inconsistencies can and should be ironed out , but I am slow - and easily distracted. Don't wait on me to do it.

What I post here tonight is what I have so far. I need to read some instructions before I can do any more. I would like to be able to supply a project ready for PCB layout, but I need to work on my library parts integration, and consistency. Whew, that's all for now. Sorry about the long-winded monologue.
If you have questions aboout my additions, feel free to holler - but remember that Shawn was the original designer .
Good Luck