Electronic function selector

Re: electronic function selector

dudu said:
Hi Chris
I prefer by IC's circuit , but it can be by relays......

if I could to suggest
better choose relays, thae are almost distortionless.
ICses will distore the clean sound sound up to 0,01%THD.

Anyway I am interested too.

I think that the problem will be solved if anyone could design good switching and steering circuit.

I thought many times about it.
... And my problem is only how to steering the relays from a "momentary switch-contacs".
To explain: how to steering from the switches that are not in type "switch on - switch off" but only from the short contact when pressed?
darkfenriz said:

How about 'T'-flip-flop with short impulse to clk input?

proszê jaœniej

Sorry for this part, I have to explain:

chodzi mi o coœ takiego: jest 5 styków (styków, nie prze³¹czników). Jak zbudowaæ uk³ad, który po chwilowym zwarciu jednego ze styków w³¹czy w³¹czy do³¹czony przekaŸnik? Mo¿e byæ dodatkowo uk³ad pamiêtaj¹cy stary wybór po w³¹czeniu zasilania.
Jeœli to siê nazywa T flipflop to jestem za:nod:

Thank for understanding!
sorry for Polish

nie wiem jak zrobiæ, ¿eby pamiêta³o, ale pomys³ mam taki:

This is an idea for 4 inputs with D-flip-flops.
The circuit is not idiot-proof, I mean pressing two at the same time can short inputs:

EDIT: not built yet, only suspect it 'should' work.;)
any comments most welcome


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Look at Analog Devices list of muxers. They have some improved versions of the DG407 with lower Ron than the industry standard parts. (ADG407 has 50 ohms Ron compared to Maxims DG407's 100 ohms Ron, and better than TI's MPC507 which is 1500 ohms Ron!)

Ive seen the Analog Devices parts used in some quite high quality gear, such as that from Arcam.

You could drive this easily using an 8 bit latch and an 8to3 encoder (74HC373 and 74HC148)

I have actually recently built a selector that would suit your purpose (it even works with remote control). It just uses 4013 flip flops and some signal diodes. It can be expanded to as large as you like, though it will bet a little inefficient (with 6 inputs it uses ~30 diodes). Here's how it works:

Have 6 inputs from switches, etc (active high), one to select each input. That is then fed to the set of the associated flip flop, as well as being fed by diodes to the reset input of all other flip flops. Hence for a 6 input selector, you need 5 diodes feeding the 5 other flip flop's resets for each input - so you have 5*6 inputs = 30 diodes. Note that you will also need a pull-down resistor (in the order of 47k) on the reset pins, otherwise it won't be held low in the absence of an input.

It is also a good idea to add a capacitor of order 0.27uF from +ve to reset on all flip flops as well, as on power up the capacitor will pass a short burst of current as it charges, resetting each flip flop, ensuring that all inputs are off when it is first turned on.

Obviously the flip flops will drive relays (which I got for $1 each!) via a suitable transistor - a BC548 is more than adequate for my purpose (relays only draw 40mA at 5V).

darkfenriz said:
sorry for Polish

nie wiem jak zrobiæ, ¿eby pamiêta³o, ale pomys³ mam taki:

try this link http://www.diyaudio.com/forums/show...4681&highlight=

your circuit is super easy but what is this flipflop circuit. Is it a certain IC or discrete circuit?

I saw that Mosfets are steering the relays, do you have some cheap suggestions for Mosfets?