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January 22, 2009
I purchased this as a guest so I apparently cant leave a review.
The build of the kit is just mediocre. The plastic parts have a wavy cut edge to them like they where cut free hand on the short ends. The buttons have tight clearances and can rub/bind a bit if your soldering was not perfect. I had to go back and “adjust” 3 of the buttons to align despite them looking straight. The bottom plate is pressing against the top of the larger capacitors. The USB connector had bent pins I had to straighten before soldering. One of the pins of the power button has zero clearance to a capacitor it is next to.
Something on mine is whistling a bit. I think its the LCD. Its not very loud and cant be heard over the fan noise of other test equipment but still a bit annoying.
The frequency seems vary accurate but the amplitude leaves something to be desired. Especially at the 5-10V range. I took these measurements using a Rigol DS1102E. I tried to confirm them with a Tektronix 2246 and Fluke 87V with varying and worse results. Everything agrees the frequency is accurate though.
Set | Out
1V | 1.08Vpp
2V | 2Vpp
3V | 3Vpp
4V | 3.88Vpp
5V | 4.8Vpp
6V | 5.68Vpp
7V | 6.6Vpp
8V | 7.52Vpp
9V | 8.48V
10V | 9.12Vpp
I guess you cant really complain for the price. I’m just at a point where I appreciate more attention to detail. Things like the wavy cut edges clearly are just sloppiness.
It does generate accurate frequencies within its spec. I suppose at the end of the day thats what you want your money to go towards in this price range.
about 2 years ago
I bought a couple of these to put between an arduino and some 12V automotive relays. Unfortunately they only are rated for up to 50mA/ch and the coil current of my relay is 75mA so I bought some of the next step up in the series the PS2502-4’s from digikey that can handle 160mA/ch.
I’m worried about the power dissipation that is 120mW/ch on both devices. The relay is going to draw 900mW (75mA * 12V) but to calculate the power dissipation of this device I just need to take Vce(sat) which is .3V on the PS2501-4 and 1V on the PS2402-4 and multiply it by Ic of 75mA right? So with the PS2402-4 I would have 75mA * 1V = 75mW and be well within the 120mW / channel rating right?
Is my reasoning here right? Is Ic just the current through the relay like I assumed? Is there any Vbe that I need to worry about (Not sure what this would be with a photo transistor).
Is it ok to drive the relay directly with the opto-isolator or should I just use it for protection and use it to turn on something like a TIP120 instead?
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