Author Topic: IMPORTANT : Updated information regarding Sound controls (Newsletter Article)  (Read 1603 times)

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Offline John Candy

Having just spent two days extensively testing my N5 on the rolling road, a couple of matters have arisen which will be of importance to anyone intending to follow the example outlined in the Newsletter.

Firstly, I have revised the specification for the whistle/horn control switch.
For some reason, the whistle control failed on the second day, making it impossible to stop the whistle (except by cutting the battery power to the sound card).
At first I thought the reed relay had failed in the 'closed' mode but after some further tests I reached the conclusion that the Pololu 752 digital switch was at fault.
Quite why I cannot say : The reed relay switching was well within its specified capabilities, perhaps there was a faulty component or a momentary overload.

I quickly assembled a new switch using a Pololu 1210 (as used in the 'chuff' switch) which is a far higher rated switch with a MOSFET output capable of handing both higher voltage and current.

I am attaching a circuit diagram to replace that printed in the Newsletter, together with the revised component list.

Secondly, while assembling a second 'chuff' switch (in this case to serve as a 'coasting' switch for a diesel railcar) I spotted an error in the circuit diagram which I had drawn  for the Newsletter (hurriedly and late at night).   On the DPDT relay, I had miscounted the pins for the switched circuit and they are displaced by one position on the diagram.

A corrected diagram is attached, together with some additional clarification on the wiring as used with my "Mac 5".

Parts Lists:

'Chuff' cut-out switch

Parts used (source)
Pololu 1210 radio controlled digital switch with MOSFET output (www.active-robots.com)
Miniature relay, double pole double throw, 5 volt (www.active-robots.com  part No. RE1)
16-pin DIP socket (to mount relay) (www.active-robots.com  part No. DC-16 PIN)
Servo lead to connect to R/C RX unit (www.active-robots.com  part No. 86230)

Digital whistle switch
Parts used (source)
Pololu 1210 radio controlled digital switch with MOSFET output (www.active-robots.com)
Reed relay single pole / single-throw 5 volt  (Maplin part no. JH12N)
Servo lead to connect to R/C RX unit (www.active-robots.com  part No. 86230)

Required for both projects : Veroboard (pierced stripboard with parallel copper tracks).
« Last Edit: June 11, 2010, 09:44:04 PM by John Candy »
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