I was not sure in which section of the forum I should post this, but I ended up posting it in the tube section because the circuit is tube- based.
I've done some electronics projects before, built a simple tube preamp for a carbon mic. I have a basic understanding of electronics and passive and active components, can read schematics and I'm quite good at soldering. I've never designed any circuits of my own though, and need help in order to make some decisions and design some relay control circuitry.
The audio circuit is based on a EF 86 and two ECC83's, and has a few different switchable pre-emphasis curves. Instead of using rotary switches, I want to use relays to switch between the different curves. Has anyone on this forum done something like that before?
I'm afraid I can't post the whole circuit right now, because the designer is a quirky little old man, and might object if I do so without his consent. Anyway, I attached a section of the schematic to illustrate my "problem".
partofphonopreschem by mrkrabbz, on Flickr
In the original design, a five-pole rotary switch with five positions is used to simultaneously switch at five points in the circuit (a - e) . My first idea was to cascade four DPDT relays for points a and b, as well c and d. The first relay would switch between a disconnected pin and the next relay. The second relay would switch between the next two relays, which would yield the required 4 different paths.
I would switch the relays with some transistors controlled by an Arduino board. The Arduino will also use a LCD display to tell what preemphasis curve is in use!
An electronics shop in my town has these SMD relays on sale:
MEISEI PS-5
DATASHEET
Are these relays good enough to be used in a sensitive circuit like this phono preamp? Are there any general considerations that would forbid using (cascaded) relays and/or the Arduino in this context?
I will appreciate any kind of input!
cheers,
Bob
I've done some electronics projects before, built a simple tube preamp for a carbon mic. I have a basic understanding of electronics and passive and active components, can read schematics and I'm quite good at soldering. I've never designed any circuits of my own though, and need help in order to make some decisions and design some relay control circuitry.
The audio circuit is based on a EF 86 and two ECC83's, and has a few different switchable pre-emphasis curves. Instead of using rotary switches, I want to use relays to switch between the different curves. Has anyone on this forum done something like that before?
I'm afraid I can't post the whole circuit right now, because the designer is a quirky little old man, and might object if I do so without his consent. Anyway, I attached a section of the schematic to illustrate my "problem".

partofphonopreschem by mrkrabbz, on Flickr
In the original design, a five-pole rotary switch with five positions is used to simultaneously switch at five points in the circuit (a - e) . My first idea was to cascade four DPDT relays for points a and b, as well c and d. The first relay would switch between a disconnected pin and the next relay. The second relay would switch between the next two relays, which would yield the required 4 different paths.
I would switch the relays with some transistors controlled by an Arduino board. The Arduino will also use a LCD display to tell what preemphasis curve is in use!
An electronics shop in my town has these SMD relays on sale:
MEISEI PS-5
DATASHEET
Are these relays good enough to be used in a sensitive circuit like this phono preamp? Are there any general considerations that would forbid using (cascaded) relays and/or the Arduino in this context?
I will appreciate any kind of input!
cheers,
Bob