Relay operating at 10mhz?
Andy "A Man With A Plan"
Posts: 45
Is it possible to have a BS2 to control a solid state relay to generate a 10mhz signal?
Andy "A Man With A Plan"
Posts: 45
Comments
1) Commercial SSRs are designed for switching 60Hz power. They are not fast enough to switch anywhere near 10MHz.
2) A BS2 is not fast enough to control anything at 10MHz. The execution time of very simple operations is on the order of 100us.
I strongly suggest that you begin to read datasheets and manufacturer's specifications. You're asking questions that you should be able to start answering for yourself with the information readily available over the Internet. Parallax has a webpage that compares different Stamp models and lists the execution speed of the various Stamps in table form. It lists the speed of the BS2 as around 4,000 instructions per second. That would answer your 2nd question immediately. If you were to search for solid state relays using Google, you'd find some major manufacturers like Crydom. In their datasheets, they indicate that their AC SSRs will work up to 400Hz, but with several times the leakage current found at 60Hz. That implies that faster may be even worse. Their DC SSRs switch on in roughly 1ms and off in roughly 1/3ms. You figure the math.
Next question you have, do a little research first and, if you don't understand what you find, ask about that too. You'll learn more and you'll be able to ask better questions.
Post Edited (Mike Green) : 12/7/2009 12:20:29 AM GMT
The easiest way to control a 10MHz signal from a slow processor is to generate the signal externally (fairly easy) then use another device to control the signal being present or not. For that, I'd suggest you add an AND gate DIP as an external package. Feed the 10MHz signal to one input, then connection an I/O pin to the other side of the AND gate. The result will be 10MHz when the I/O pin is asserted ("ON" or "1") and nothing otherwise.
As for all the other comments -- learn to read data sheets, and familiarize yourself with the entire 74xx serial of TTL chips.
And to certain commenters, learn to think outside the box.
But I liked your answer too.
I do as well, but sometimes an "outside the box" suggestion is needed to move the discussion in a direction that leads to a solution. It's very unlikely that a 10MHz signal is needed for anything that also requires a SSR. There are a LOT of solutions in lower power spaces. Just gotta pick one.
[noparse][[/noparse]quote]But I liked your answer too.
Glad I was able to provide something useful!
1) It is possible to saturate the relay coil such that it will hold only one state (permanently magnetized until the current is removed) as it was not designed to switch at 10MHz. Additional filtering will have to be applied to the relay coil to reduce voltage transients from back feeding into the power supply which can harm the control electronics.
2) Relay contacts were not designed to switch at a 10MHz rate. Along with problem 1), this could cause relay contacts to arc over, depending upon the current and voltage being switched. This can cause problems in the control electronics as the arcing can induce voltage transients in the power supply both upstream and downstream of the relay.
3) Much easier to design stand alone logic to switch/oscillate at 10MHz. 5VDC crystal oscillator modules already exist for less than $10 (Jameco) to establish your timebase. You will probably end up using a high power transistor to perform the switching. Again, you will have to have filtering to control the RFI and EMI generated by the switching logic.
Why a relay????
73,
kevin
kc6pob
-Phil
-P.