Re: International standards

That would work with an AC source for the lamps, but then it's not really the pulse width that's being controlled, but the conduction angle.

I still think a single pwm output feeding a control gate for each light string is the ticket. OP's already got a 38 VDC supply.

You can get zero crossing opto couplers or build it into the triac circuit. Any significant delay from zero cross to turn on cill generate EMI.

Hello

I have to make a simple radio link using a CC1020. I have a development kit and SmartRF 5.3 software. I have also made 2 boards with max232 just to have a level converter because the data I want to send using this link is going to be taken from PC. So I use DIO as input and DCLK as an output pin just as writen in manual.

The problem is:

I always have a strange rectangular signal on output, but not simetrical, rather stochastic. It does not depend on the data format. Even if I use Manchester or NRZ I have on the receiver the same signal (on DIO, because on NRZ and Manchester DCLK is a normal clock) I am really not sure If the TX part talks.

Do you know what to do to go on with the design, because my boss hates looking at me, when something like this happens :)

Best wishes

Piotr

Large values are smaller than nonpolarized types.

Low leakage, high reliability if properly applied. Designer may have thought that it increased his prestige if his circuit used high priced parts.

I am quite sure the designer pulled the value out of his uh.. oh never mind.

They are spendy.

You should first investigate what can be done with good layout and an extra board layer or two, if the board is just two sided. Then, after layout related problems have been brought under control, you can think about circulating currents and how to supply them locally with capacitors and what values would be appropriate. Ceramic caps are available in sizes and with competitive costs for all but the larger tantalums. And a combination of an aluminum electrolytic and ceramic may exceed the performance of single tantalums at lower total cost.

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Unconnected.

John

The issue I see is that when the mosfet is conducting, the voltage across it is small. Thus, its not going to be a very good source for generating 5V. Thus, he needs another source, which could be a battery, or another bridge. However, if its a bridge, and he connects the grounds, he is in trouble for obvious reasons. The second bridge will conduct, causing lots of wierd behavior.

I like PWM for this application, actually, using a triac. The basic stamp would have to use two pins rather than one, though. One for an input to determine zero crossing, and one to control the triac.

-- Regards, Bob Monsen

A friend of mine bought one of their kits once and it didn't work. Myself and another party looked his work over. The kit was plain JUNK in design. He called Ramsey to see about getting it corrected, they wanted almost twice what he paid for the kit in labor. If you have a schematic, maybe you could post in Binaries and some of us could look at it and get an idea of the layout and give you more productive advice.

L.

I was working on a proper derivation but ended up with an extra term and couldn't divide through by Vin to get Vout/Vin.

The above approach has errors and beta, which I wouldn't use isn't specified for that transistor, though there is a g_m curve.

For a current source load, gain is limied by the early voltage. I think the proper approach is to select a current for the 117 and use

Ic = g_m*Vin - Vin being Vbe and

I_R2 = Ic + I_L

to get the load current and thus the voltage. It's an approximation IMO, but It's quick.

Let me also suggest the term "cord wart" for the kind that is a box midway along a cord...

Keep in mind that the 'transistor' is an integrated circuit, LM195.

Hey all;

I'm using a high speed opamp as a voltage follower. I'm not using the offset null pins - should I tie them to ground or leave them unconnected?

Thanks

With almost all opamps, leave them unconnected. What chip are you using?

Offset pins often have higher voltage gain than the normal inputs do, so keep signals that might capacitively couple to them well away.

As I said b4: In solidworks determine the pcb outline (including any non electronic components slots, holes, etc) then just export it to the e-cad package as a dxf. This is your board ouline layer which you never need touch - just leave it all alone on its own layer and do the other e-cad on other layers. Loads of e-cads import dxf's and solidworks exports them.

Right. THat's why the transconductance isn't 40Ie and oops, I said Vbe which isn't right.

I hit the dead end when I got to:

them

for

connects

bridge

I'd say he just waits for some time after each zero crossing, and triggers the triac. By increasing the time after each zero crossing, he dims the bulbs in a way that doesn't depend on the current or RC constants. The pulse width of on time for the lamp is being 'modulated' by the PIC :)

an

That is true. The MOC3063 does a good job of this. You can then control the output by keeping it off for more cycles each time.

OTOH, the other scheme is actually pretty easy to do. I once built a hands off lamp dimmer that controlled the brightness of a lamp that way using a PIC, a triac, and an IR proximity detector. Move your hand closer to dim the lamp. Two quick swipes turns it on or off at the same value it had before.

It used a 4.7MEG resistor from Line to measure the zero crossings.

ROFL!. John, you've just made my day :-) regards john

current

We can't isolate Vo/Vi so there is no gain because gain is defined as Vo/Vi. Not all circuits have gain, this one doesn't, which is very strange considering the title.

"little billy" skrev i melding news: snipped-for-privacy@posting.google.com...

The LM117 and the R2 together, is a current source provides the same current whatever voltage on the "output". Idealy, the gain is infinite, because you shouldn't be able to make an input current so precise so that the outpot voltage stays stable (even for a short time) between maximum and minimum. (not considering rise/fall time).

You may want to check in the alt.pirate.radio news group for builders of the kit.