Prop2 information request; wiring/programming?

[JonnyMac]

My mistake, I was thinking of something else: the series protection resistors are 100 ohms.

[Friz]

Hi JonnyMac,

Thank you for the fast reply!  :)

[Friz]

Hi JonnyMac,

Usually, whenever a relay is used in a circuit a protective diode is installed across the coil to short the HV spike that is
generated when the coil is switched OFF.
The project within this thread places +12VDC on one side of the coil thru the lamp relay contact and uses the control path via the PCB output for each of the relays.
Where is the best place to install a diode for each relay so it will maintain the required removal of the HV spike when the coil is switched OFF.

I realize the wiring is generally common but this configuration has a slightly different concept since a control relay (lamp test) is used.
Any help, text or pictorial would be greatly appreciated.

Thank you,

Frank

[JonnyMac]

The ULN has diodes built in -- that's why I didn't put extras in the circuit.  If you want to add extras, however, there's no harm, and it would probably be best do do it right across the relay coils.  Make sure that you connect the cathode side of the diode (I suggest something beefy like a 1N4001) to the V+ side of the coil, the anode side to the OUTx side of the coil.

[Friz]

Hi JonnyMac,

Thank you for the extremely fast response along with the info concerning the ULN.  :)
I am in the process of designing a few PCBs using press-n-peel that will be used in conjunction with the heart of the project (PROP2)!

Although, the latter will take some time to complete etc...

Frank  :)

[JonnyMac]

Unless you *really* like messing around with chemicals I would suggest using a service like ExpressPCB to handle the boards.  You can draw them on screen, adjust to your heart's content, and then order the boards via the Internet.  If they work well, you can order more.  I use ExpressPCB all the time.  Not perfect, but WAY better than hand etching PCBs.

[Friz]

Hi JonnyMac,

I only make a few boards a year depending on the project.
Press-n-peel only requires a decent laser printer, the etchant is the only chemical used and i always play it safe etc...

Although, i agree with your opinion since the whole process can become frustrating when the press-n-peel does not transfer properly.

:)